PCSYSCON
PC Compatible
System Controller
Technical Manual
2192-09065-000-000
Page 1
J278 PCSYSCON
Product Information
Full information about other Arcom products is available via the FFaaxx--oonn--DDeemmaanndd
SSyysstteemm, (Telephone
Numbers are listed below), or by contacting our WWeebbSSiitteein the UK at: wwwwww..aarrccoomm..ccoo..uukkor in the US at:
wwwwww..aarrccoommccoonnttrroollss..ccoomm
UUsseeffuull
CCoonnttaacctt
IInnffoorrmmaattiioonn
CCuussttoommeerr
SSuuppppoorrtt
SSaalleess
Tel: +44 (0)1223 412 428 Tel: +44 (0)1223 411 200
Fax: +44 (0)1223 403 400 Fax: +44 (0)1223 410 457
E-mail: support@arcom.co.uk E-mail sales@arcom.co.uk
or for the US
E-mail icpsales@arcomcontrols.com
UUnniitteedd
KKiinnggddoomm
Arcom Control Systems Ltd
Clifton Road
Cambridge CB1 4WH, UK
Tel: 01223 411 200
Fax: 01223 410 457
FoD: 01223 240 600
UUnniitteedd
SSttaatteess
Arcom Control Systems Inc
13510 South Oak Street
Kansas City MO 64145 USA
Tel: 816 941 7025
Fax: 816 941 0343
FoD: 800 747 1097
FFrraannccee
Arcom Control Systems
Centre daffaires SCALDY
23 rue Colbert
7885 SAINT QUENTIN
Cedex, FRANCE
Tel: 800 90 84 06
Fax: 800 90 84 12
FoD: 800 90 23 80
GGeerrmmaannyy
Kostenlose Infoline:
Tel: 0130 824 511
Fax: 0130 824 512
FoD: 0130 860 449
IIttaallyy
NumeroVerde:
FoD: 1678 73600
BBeellggiiuumm
Groen Nummer:
Tel: 0800 7 3192
Fax: 0800 7 3191
NNeetthheerrllaannddss
Gratis 06 Nummer:
Tel: 06022 11 36
Fax: 06022 11 48
The choice of boards or systems is the responsibility of the buyer, and the use to which they are put cannot be
the liability of Arcom Control Systems Ltd. However, Arcoms sales team is always available to assist you in
making your decision.
© 1996 Arcom Control Systems Ltd
Arcom Control Systems is a subsidiary of Fairey Group Plc.
Specifications are subject to change without notice and do not form part of any contract.
All trademarks recognised.
Arcom Control Systems Ltd
operate a company-wide
quality management
system which has been
certified by the British
Standards Institution (BSI)
as compliant with
ISO9001:1994
Contents
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Section 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
The PCSYSCON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
About the PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Features of the PCSYSCON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Using Signal-Conditioning Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
What to do Next . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Section 2. The PCSYSCON I/O Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
The I/O Pointer Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
How the PCSYSCON Appears in PCbus I/O Space . . . . . . . . . . . . . . . . . . . . 9
The Registers on the PCSYSCON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
How to Write to the Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
DAC Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
General Purpose Digital I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Mask Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Watchdog Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Section 3. Using the PCSYSCON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Installing the PCSYSCON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Installing Multiple PCSYSCONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
A Quick installation Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Default Link Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Voltage Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Temperature Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Option Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Digital I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Section 4. Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Section 5. Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Installation for CE Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Appendix A. Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Appendix B. Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Appendix C. Component List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Appendix D. Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
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J278 PCSYSCON
Revision History
2192-09065-000-000
Revision History
Page 3
J278 PCSYSCON
Manual
V1 Iss 1
V1 Iss 2
V1 Iss 3
Issue A
V1 Iss 2
V1 Iss 3
V1 Iss 3
V1 Iss 3
910207 First Draft Created
910222 First Release in this format
961023 [ECO2024]
980119 [ECO2684]
PCB Comments
J278 PCSYSCON2192-09065-000-000
Page 4
Section 1. Introduction
The PCSYSCON
The PCSYSCON is a plug-in board for PC-compatibles. It can
measure various conditions inside your PC and produce several
sorts of alarm signals. It can also produce alarms from external
analogue and digital signals, and it has eight general-purpose digital
input and eight digital output lines.
The purpose of the board is to give advance warning of potential
trouble in industrial PC systems. There are many possible sources
of trouble, such as an aging or overloaded power supply, excessive
temperature rise or programs that have crashed when controlling
some critical process. The PCSYSCON can detect these conditions
when properly set up.
However, a note of caution. If you are going to use the PCSYSCON
to detect a potential problem, you must set it up and then create or
simulate the problem. You will then be able to prove that your
hardware and software can indeed detect the problem and take
appropriate action. No amount of hardware is going to help if the
program or operators fail to take any notice when a problem is
detected.
About the PC
PC-compatibles are often used for I/O intensive applications with
boards such as the PCSYSCON. Unfortunately, some features of the
PC can make life difficult for users. We have tried to address these
problems with the PCSYSCON. For example, it is sometimes difficult
to find I/O address space in a PC - we have created a unique pointer
addressing scheme which only takes up two bytes of PC I/O space
but allows hundreds of I/O locations on the board. Another common
problem is that of getting large numbers of cables safely into a PC.
Arcom designed a signal-conditioning system which has been in use
on other buses for some years; this system is also available for the
PCSYSCON.
Features of the PCSYSCON
The PCSYSCON has voltage and temperature monitors, a
watchdog, external optoisolated inputs and analogue input trips. It
can sound an internal buzzer, switch a relay or trigger a PC interrupt
on detecting an alarm condition. Alarm conditions are also output on
the 50-way I/O connector, which also carries the eight general-
purpose digital inputs and eight outputs.
The voltage and temperature monitors detect under-voltage and
over-temperature conditions. They are designed to operate even if
the program in the PC has crashed completely - they do not rely on
a background program operating continuously. Their alarm levels
can be set up in software.
The watchdog monitor function is intended to be integrated into your
software. The principle is that your application program starts the
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Section 1. Introduction
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J278 PCSYSCON
watchdog, and must then access an I/O port at regular intervals to
stop the watchdog timing out. If your program fails to do this the
watchdog times out and the alarm operates, indicating that your
program has crashed. Once the watchdog has been started it cannot
be stopped by anything except a complete system reset. The
watchdog can be set to operate with either a two second or a ten
second timeout.
The two "option" inputs OPT1 and OPT2 can each be used for either
an analogue or an optoisolated digital input. OPT1 can operate an
alarm when the voltage is lower than that set on a potentiometer or
when there is no current into the optoisolator. OPT2 works the other
way round.
Each of these monitoring functions can be set individually to operate
the buzzer, relay or interrupt by writing to mask registers. The status
of these registers and of the monitoring functions can be read back
at any time.
The PCSYSCON can also be used for digital I/O. One group of eight
lines on the connector can be read directly as inputs. Another group
can be written to as outputs.
It is vitally important to be able to do some form of self-test with
industrial equipment. The PCSYSCON contains many features to
assist in this. At the lowest level the PCSYSCON has two light-
emitting diodes (LEDs). These are intended for use on initial
installation, since they will not usually be visible inside the PC. The
red LED flashes each time the board is accessed. This is useful to
check that the board is at the correct address. The green LED can
be switched on by a user program. It can be used in a power-on test
routine to indicate to a technician that the board has passed. In
addition, the PCSYSCON has an identifier code at a fixed location in
the I/O map. This can be used to identify a board at a particular
PCbus I/O location. The code for the PCSYSCON is 80
(hexadecimal) (128 decimal).
A 50-way D-type connector is used to connect to the PCSYSCON.
This allows a ribbon-cable to connect to individual cable connectors
or to other boards which either modify the signal in some way or
contain other types of connectors. These are called signal-
conditioning boards.
The 50-way connector is compatible with Arcom's signal-
conditioning scheme, which lets you connect dozens of different
types of signal-conditioning boards to process signals to or from the
PCSYSCON.
There are two 10-way headers which may be used for some I/O
inside the PC. They carry a subset of the signals on the 50-way
connector.
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Section 1. Introduction
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J278 PCSYSCON
Using Signal-Conditioning Boards
In an industrial environment there are many signals which it is
unsafe to let into your PC. Examples are signals at high voltage such
as mains, or signals with a lot of superimposed noise. This latter
category includes most signals that exist in a factory. Another
potential problem is that the PC may not be able to supply enough
power to drive some equipment directly. Also the signals may be on
cables which cannot be physically connected to the PC because
they are just too big and cumbersome.
The Arcom signal-conditioning system was designed to solve these
problems. In essence the idea is extremely simple. All Arcom digital
I/O boards have a standardised connection to a 50-way ribbon
cable. TTL-level signals (together with +5V, +12V and -12V) are
used on this cable. The cable connects one digital I/O board to one
or more signal-conditioning boards. These have a 50-way ribbon-
cable connector at one end and a heavy-duty connector at the other.
The heavy-duty connector can plug into a terminator mounted in a
rack; the terminator can have screw terminals.
A wide range of signal-conditioning boards is manufactured by
Arcom (and other manufacturers). Many functions are available -
optoisolation, relay outputs, Darlington and FET drivers, switch and
keyboard inputs are just a few of them.
What to do Next
If you want to see something happening as soon as possible, turn to
Section 3 for information on how to install the PCSYSCON in your
PC. When you have installed it, run the driver software as described
in Section 4.
If you want to know more about how the PCSYSCON works, Section
5 contains details of the circuitry.
If you are going to be programming the PCSYSCON, Section 2 has
information on the I/O map.
In all cases, Section 3 contains much useful information.
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Section 1. Introduction
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J278 PCSYSCON
Note: All addresses and data values in hexadecimal in this
manual are followed by the letter H.
J278 PCSYSCON2192-09065-000-000
Section 1. Introduction
Page 8
Section 2. The PCSYSCON I/O Map
The I/O Pointer Scheme
There is a serious shortage of I/O space in most PCs. This can be a
real limitation if I/O boards have lots of functions and hence lots of
registers, like the PCSYSCON. The I/O pointer scheme used on the
PCSYSCON and other Arcom PCbus boards solves this problem.
In outline, to access a register on the PCSYSCON you must first set
up a pointer to it by writing a byte to the 'base address' of the
PCSYSCON. After that, you can read from and write to the register
that is pointed to, by accessing the byte at the base address + 1. The
base address is the address that is set up on the address switches,
subject to the constraint that it must be an even address (an odd
address set up on the switches is treated by the PCSYSCON as the
next lower even address).
Given that the pointer value is a byte, there are 256 possible
registers on a PCSYSCON. Obviously, not all of them are actually
used. In fact, on most boards very few of them are used, but the
possibilities for expansion are there.
In order to allow standardisation of software some register
addresses have been defined for all Arcom PCbus I/O boards. In
particular, the top half of the 256 byte space has been defined as
'special function' register space, and the bottom half as 'I/O' register
space. The special function registers are mostly devoted to self-test,
checking, security and diagnostics. The I/O registers are the ones
which the board is there for: in this case monitoring, alarm and
input/output functions.
The next two sub-sections describe the register allocations in detail.
How the PCSYSCON Appears in PCbus I/O Space
The PCSYSCON occupies two bytes in PCbus I/O space. They start
on an even byte boundary. The lower byte contains the pointer and
can only be written to. The upper byte contains the data and can be
read from or written to.
The address switches define where these two bytes are in PCbus
I/O space. The switches set the address of the lower of the two bytes
(the base address); the upper byte is one byte up from the lower.
Another way of saying this is that the board can only be addressed
at even byte boundaries and takes two consecutive bytes of I/O
space.
To set the address simply rotate the switches until the desired base
address is visible, reading them left to right, as text is normally
viewed. For example, to set up an address of 10CH, the left-hand
switch is set to 1, the centre switch to 0 and the right-hand switch to
C. Note that the addresses are in hexadecimal.
The problem comes in finding what to set the switches to. Many PCs
are not supplied with any information about what I/O devices are
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Section 2. The PCSYSCON I/O Map
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J278 PCSYSCON
already installed at particular addresses. There are several ways
round this. Firstly, try running the board at address 180H(see
Section 3 for installation information). This is often unused. If you
can't get any information from the PC manufacturer, run a program
like Quarterdeck's Manifest, which makes a reasonable attempt to
discover the addresses of common peripherals. Finally, see Section
3 for fault-finding information.
The Registers on the PCSYSCON
The following table shows the I/O registers on the PCSYSCON.
The following table shows the special function registers on the
PCSYSCON.
How to Write to the Registers
It is useful to remember that the pointer register only needs to be
written to once if only one register is read or written. This means that
I/O can then be done with byte reads and writes. However, if your
program is continually changing registers it must write a new pointer
value each times it accesses a new register. This can be done by
writing a pair of bytes as a word, because the CPU in a PC does
word writes to the bus (which is one byte wide) by writing the lower
byte first, thus setting up the pointer register first.The sub-section A
Quick Installation Test shows the basics of how to write to the control
register.
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Section 2. The PCSYSCON I/O Map
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J278 PCSYSCON
Pointer Value
09 STARTW
STATUS
RETRIGW
BUZM
RELM
INTM
G1IN
G0OUT
DACTEMP
DAC-12
DAC+12
DAC+5
W
R
W
R/W
R/W
R/W
R
W
R/W
R/W
R/W
R/W
Start watchdog and set final timeout
Read board status
Retrigger watchdog
Buzzer mask
Relay mask
Interrupt mask
Read from group 1 inputs
Write to group 0 inputs
Set temperature comparison
Set -12V comparison
Set +12V comparison
Set +5V comparison
08
08
07
06
05
04
04
03
02
01
00
Register Name Read/write Comments
Pointer Value
81H Board Ident
User LED
R
W
Reading this should always give a value of 80H
for the PCSYSCON
Writing 01 switches the green LED on. Writing 00
switches it off.
80H
Register Name Read/write Comments
DAC Registers
The DAC registers (DAC+5, DAC+12, DAC-12 and DACTEMP) set
the levels at which an alarm can occur if the alarm mask registers
are set. For example, the +5V power line in the PC is compared with
the voltage produced by the DAC+5 digital-to-analogue converter
(DAC). If the +5V power line is below this voltage a bit is set in the
STATUS register. This can be read at any time. In addition, if the
BUZM alarm mask register is programmed to allow a power fail to
sound the buzzer then this will also sound.
Alarms from the three power-line monitors DAC+5, DAC+12 and
DAC- 12 are combined into one signal PFAIL for the alarm mask
registers. The over-temperature signal (from the DACTEMP register)
is a separate bit in the alarm mask registers.
It is possible to use the DACs as analogue-to-digital converters to
measure the power line voltages and temperature. To do this, simply
disable the PFAIL and OTEMP alarms and write to the DAC register
of interest, reading the corresponding bit in the STATUS register.
The value at which the bit flips corresponds to the voltage or
temperature.
To maintain reasonable accuracy, each DAC is scaled differently.
General-Purpose Digital I/O Registers
These registers are accessed at pointer value 4. Writing a byte to
pointer value 4 sets bits on the 50-way connector PL2, and reading
pointer value 4 reads bits on this connector. A high bit (=1)
corresponds to a high TTL level on the connector pins - there is no
inversion.
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Section 2. The PCSYSCON I/O Map
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J278 PCSYSCON
Pointer
3 DACTEMP Temperature high 1 bit=0.482C
1 bit=-60.53mV
1 bit=60.73mV
1 bit=24.22mV
-12V supply low
+12V supply low
+5V supply low
DAC-12
DAC+12
DAC+5
2
1
0
Name Function Scaling
Mask Registers
There are three mask registers INTM, RELM and BUZM each with
the same bit meanings, as follows.
INTM is at pointer value 5 and controls interrupt generation. The
actual interrupt to be generated is set by LK1.
RELM is at pointer value 6 and controls relay operation. LK2 controls
whether the relay is normally on or off.
BUZM is at pointer value 7 and controls the operation of the buzzer.
Each mask register is independent, so that, for example, the buzzer
can be made to sound if the set temperature is exceeded while the
relay operates if there is a watchdog timeout.
Mask registers can be read and written, so your software can check
that the desired masks have been set up.
STATUS register
The STATUS register is at pointer value 8 (read). It contains
information about what is happening to the board. The bit patterns
are similar to those in the mask registers. In general a high bit
indicates a problem.
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Section 2. The PCSYSCON I/O Map
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J278 PCSYSCON
Bit
7
6
PFAIL
OPT2
OPT1
WATCH
OTEMP
power-fail
option 2
option 1
Watchdog
Temperature
Not used
Not used
Not used
Alarm if one or more of the three power lines is
below the DAC voltage.
Alarm if option 2 input is triggered
Alarm if option 1 input is triggered
Alarm if watchdog timeout
Alarm if temperature exceeded
5
4
3
2
1
0
Name Function Comments
Bit
7
6WDIS
-12L
+12L
+5L
OPT2
OPT1
WATCH
OTEMP
Watchdog
-12V problem
+12V problem
+5V problem
Option 2
Option 1
Watchdog
Temperature
High if the watchdog has never been started
High if -12V line low
High if +12V line low
High if +5V line low
High if option 2 input triggered
High if option 1 input triggered
High if watchdog timeout
High if temperature exceeded
5
4
3
2
1
0
Name Function Comments
All of these signals except for WIDS are available in inverted form on
the 50-way connector Pl2. WDIS is replaced by an inverted version
of the buzzer signal.
Watchdog Registers
Two registers control operation of the watchdog. The STARTW
register at pointer register 9 (write) starts the watchdog with either a
two or a ten second timeout period. Only one bit (bit 0) has any
meaning in the STARTW register. If this is a 1 the longer timeout
period is selected. If it is 0 the shorter period is selected.
The RETRIGW register at pointer value 8 (write) must be written to
in order to prevent the watchdog timing out. Any value may be
written. Once the watchdog has started it cannot be stopped. This is
because otherwise software that had crashed could have activated
the routine that stopped the watchdog, thus removing the protection.
The WDIS bit in the STATUS register is a 1 until the watchdog has
been started.
It is recommended that your watchdog retriggering routine has the
following characteristics:
It is not callable routine or function, but is in-line code in the main
program loop
It is not triggered by an interrupt
It is executed once in the main program loop
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Section 2. The PCSYSCON I/O Map
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J278 PCSYSCON
J278 PCSYSCON2192-09065-000-000
Section 2. The PCSYSCON I/O Map
Page 14
Section 3. Using the PCSYSCON
Installing the PCSYSCON
The PCSYSCON contains CMOS circuitry and can be damaged by
static electricity, as can your PC. When installing, DO NOT touch the
gold edge fingers, but DO touch a metal part of your PC before
picking up the PCSYSCON. DO NOT place the PCSYSCON onto
plastic surfaces, particularly polystyrene or polythene.
The mechanical part of installation is quite simple. In most cases it
involves switching your PC off, taking its cover off, finding a spare 8-
bit I/O slot and inserting the PCSYSCON into it. However, some PCs
have different ways of doing this, so you must read your PC manual
and follow its instructions.
Initially we suggest that you do not use interrupts, so remove LK1.
Set the switches to 180 and power your PC up. Watch the LEDs on
the PCSYSCON while it powers up. You may see the red LED flash
once. This simply means that the BIOS startup program in your PC
is checking through I/O space to see if any boards are there, and is
nothing to worry about. On the other hand, if your PC fails to boot or
the red LED flashes continuously, you will need to change the
PCSYSCON base address (see Addresses below for suggestions).
If your PC does fail to boot up, power down, remove the PCSYSCON
and power up again to prove that the problem lies with the
PCSYSCON rather than some disturbance created by your
installation procedure, such as a loosened cable connector, for
example.
Addresses
Although PCs differ in their available I/O address space, some
generalisations are possible. There is usually space between 100H
and 1FFH. Addresses 300H to 31FH are (notionally) assigned to an
I/O prototyping card, so if you don't have one these are also free.
Avoid addresses below 100H. Remember that many PCs 'wrap'
addresses above 3FFH, so that 400H is treated as 000H, which
won't work.
It is not usually necessary to remove the PCSYSCON from the PC
in order to change the address. Unless your PC is very cramped
internally it is possible to rotate the address switches to change
address with the PCSYSCON still installed.
Installing Multiple PCSYSCONs
This is just like installing a single one, except that they must all be
installed at different addresses. The most obvious scheme is to
install them at consecutive addresses, remembering that each
PCSYSCON takes up two bytes of I/O space. This is also what the
Arcom software drivers expect. For example, install the first one at
180H, the second at 182Hand so on.
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J278 PCSYSCON
If you are installing more than one type of PCbus I/O board it makes
sense to keep all boards of each type at consecutive addresses.
Don't forget that other boards may take up more than two I/O
address locations. If you are going to use interrupts you have two
choices. Either all boards can share the same interrupt line or you
can jumper one board to IRQ2 and one to IRQ3 (this implies two
boards maximum). More of this later.
A Quick Installation Test
It is very easy to test the PCSYSCON with the DEBUG program to
show that it is at the address you thought. Assume that the address
is 180 H.
Run the DEBUG program by typing
DEBUG <RET>
At the prompt, type
o 180 80 <RET>
The red LED should flash once, showing that you have accessed the
PCSYSCON. In fact, this command has made the pointer point to
the green (user) LED register. To switch the green LED on, type
o 181 1 <RET>
and to switch it off, type
o 181 0 <RET>
To exit from DEBUG type
q <RET>
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Links
There are two functions defined by links on the PCSYSCON: where
the interrupts go to on the PC and what the normal relay state is.The
links are defined by pushing little blue jumpers onto pairs of pins.
Link 1. Where the interrupts go to on the PC
This is a group of six pins just above the PCbus connector. The
jumper must be inserted vertically, which means that there are four
possible situations, A, B, C and no jumper inserted.
•LK1A sends the interrupt to PCbus IRQ2.
•LK1B sends the interrupt to PCbus IRQ3.
•LK1C sends the interrupt to PCbus -IOCHCHK.
(Note that this is normally intended to generate a non-maskable
interrupt, and may well halt the PC.)
No jumper means that the PCSYSCON cannot generate any
interrupts.
If you intend to use the Arcom driver software it may be necessary
to insert a jumper into one of these link positions. See the section on
driver software.
Interrupts can only be generated if the mask register INTM is
appropriately enabled.
We recommend that you do not insert a jumper into LK1. Change
this if you intend to use interrupts and are experienced at writing PC
interrupt-handling software, or possibly if you are using the Arcom
drivers.
Default Link Position
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J278 PCSYSCON
A B C
LK1
LK2
BA
Link 2. Relay state
This is a group of three pins. The jumpers are also inserted
horizontally, and there are two possible positions, labelled A and B.
Link 2A keeps the relay on when there is no alarm and off otherwise,
and link 2B does the opposite. This is so that the power-up state can
be chosen without running any software.
Connections
Connections to the board are made by a 50-way D type connector.
It is usual to use a ribbon-cable (insulation displacement or IDC)
connector to plug into this, so that all 50 wires are connected at
once. This point is mentioned because there is some confusion
about how 50-way D connector pins are numbered. Before IDC 50-
way D connectors became popular the conventional numbering was
to number the pins incrementing parallel to the long edge of the
connector. This number is often moulded into the plastic next to each
pin. Ribbon cables, however, are numbered sequentially from the
stripe at one edge. This is not compatible for mechanical reasons
with the original D numbering system.
Because most people will use ribbon cables with this board we have
given connection details in terms of the ribbon-cable pins that will be
connected when an IDC 50-way D connector is plugged in. They are
referred to as RCx where x is a number between 1 and 50. For ease
of reference the corresponding D connector pins are also shown on
the circuit diagram and in Appendix B.
Voltage monitoring
The three power-line voltages +5V, +12V and -12V are compared
with the voltages from three DACs. If the power-line voltages drop
below the DAC voltages bits are set in the STATUS register. The
PFAIL signal is then generated which is allowed to trigger alarm
signals depending on the mask bits in the MASK registers.
It is possible to set the DAC voltages very close to the actual
voltages. This is a bad idea for several reasons. Firstly, voltages in
a PC can fluctuate by tens or even hundreds of millivolts in normal
operation, for example if a drive starts up. Secondly, digital noise on
the supply lines and on the PCSYSCON board means that the
instantaneous voltages measured are not necessarily the average
voltages. Finally, most PCs will operate at voltages quite a lot lower
than normal, especially on the +12V and -12V lines. Suggested
values for setting the DAC voltages are 4.6V for DAC+5 and 11.4V
for DAC+12 and DAC-12. However, it is your responsibility to set
them to the values which will give most warning of power failure and
least false alarms.
The sub-section about the DAC registers has the conversion factors
between bytes sent to the DACs and DAC output voltages.
For example, to make the +5V monitor trigger at 4.6V, send 191
(decimal) or BE (hex) to pointer 0.
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J278 PCSYSCON
It is well worth using the DACs as explained earlier to measure the
voltages in your PC. The example software has a simple program to
do this.
Temperature monitoring
The PCSYSCON has a on-board temperature monitor to measure
the internal temperature of the PC. This generates an alarm when
the temperature is in excess of that set by the voltage from the
DACTEMP DAC. The correct temperature to set depends on
ambient temperature, fan cooling efficiency and PC design. It is a
good idea to measure temperature rise for some hours after switch
on using the program mentioned above.
Option inputs
The two option inputs can each be used with either analogue or
opto-isolated digital inputs. They are intended for use with power-fail
signals from power-supply units, fan-fail signals from electronically-
controlled fans, or general-purpose alarm inputs. The difference
between Opt1 and Opt2 is that one works in the presence of the
signals and the other works in their absence. Either or both can be
masked out by the mask registers.
In analogue input mode the single-ended analogue signals are fed
to comparators whose trip points are set by potentiometers VR1 (for
Opt2) and VR2 (for Opt1). LEDs D7 and D6 indicate when the trip
points are reached. Trip points can be set for analogue voltages of 0
to +20V.
In digital mode, currents are passed through resistors to
optoisolators. The resistors are suitable for input voltages of 12 to
24V.
Because the analogue and digital inputs both drive the same alarm
signal, only certain combinations of signals are possible.
The analogue high and low refer to the input voltage compared to
the potentiometer setting. With no signal wire connected to the
analogue input each potentiometer can be adjusted to allow the
digital input to function. Opt2 will give an alarm with nothing
connected, however. If you do not wish to use this, make sure that
you have masked off alarms from Opt2 in the mask registers.
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J278 PCSYSCON
Digital
ignored
high
low
ignored
high
low
alarm
alarm
no alarm
no alarm
no alarm
alarm
opto current
no current
no current
opto current
no current
no current
Opt1
Opt2
Analogue Result
Digital I/O
The PCSYSCON can be used for simple digital I/O. You can read the
state of the inputs on Group 1 of the D50 connector by writing 4 to
the pointer register at 180H and reading the value at 181H (for group
1). You can write to the outputs on Group 0 of the connector by
writing 4 to 180H and writing the byte to 181H.
The state of most bits of the STATUS register is readable on the 50-
way connector . The bit pattern is the same as in the STA TUS register
except that the top bit (WDIS) from the STATUS register is replaced
with a BUZZ signal, so that a remote buzzer can be connected. All
the signals in this group of eight (Group 2 on the 50-way connector)
are active-low TTL. They can all be buffered by signal-conditioning
boards to drive remote alarms or inspected with a LED32 indicator.
Interrupts
Most interrupt lines on the PCbus are already taken up by standard
peripherals - IRQ2 and 3 are less likely than most to be used and
they can be driven by the PCSYSCON.
There are five interrupt sources on the PCSYSCON, as defined by
the bits in the INTM register.
If LK1 is not jumpered at all no interrupts will be passed on to the PC,
but you can still inspect the STATUS register.
Interrupts are not latched; your interrupt routine should do an
immediate read of the STATUS register to discover the interrupt
source. Once it has it can mask out the interrupt source with the
INTM register while it is dealing with the interrupt.
Fault finding
As described earlier, there are several diagnostic aids on the
PCSYSCON. Firstly check that the red LED near the 50-way
connector lights when (and only when) your program is accessing
the board. If it doesn't, it is likely that the address your program is
writing is not the one that the switches are set to. If this works, check
that you can turn the green LED on and off by writing to its register.
Try reading the board identification. If this is not correct but the LEDs
have been working correctly it is possible that there is another board
at the same address.
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J278 PCSYSCON
Section 4. Software
As you will probably have noticed from the examples using DEBUG,
it is easy to prove that the board is in the system at the right address.
However, the PCSYSCON requires a few initialisation bytes. To help
you to get started, a disk with example software is supplied. In order
to keep this as up to date as possible, files on the disk describe its
contents.
The file READ.ME is the first one you should look at. It contains
information on the disk organisation. You can either inspect it on
your screen by typing TYPEA:READ ME (if you are reading from
disk A), or print it to a printer. Your DOS manual has information
about the various ways of doing this.
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Section 4. Software
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J278 PCSYSCON
J278 PCSYSCON2192-09065-000-000
Section 4. Software
Page 22
Section 5. Circuit Description
The board address is selected by IC21, an 8-bit comparator , and part
of IC8. This IC, a PAL, also takes in various control signals buffered
by IC14. It generates the enable signal for IC5, the data bus buffer,
and strobe signals for IC19 and 13, which then decode pointer
addresses for the counters and registers. It also generates strobe
signals for IC6 and IC9, which holds the board identification, and IC7
which controls the green LED.
The DAC IC31 outputs are compared with the three supply rails by
IC33 and with the temperature sensor IC28. IC10,11 and 12 hold the
mask bits for the three mask registers, and IC16,17 and 18 allow
these to be read back and compared with the input signals. Alarm
signals from these ICs go to IC20 which drives the relay, buzzer and
interrupts, to IC24 which is the STATUS buffer and to IC4 which
buffers them onto the 50-way connector PL2. IC26 compares input
analogue signals and also the ramp from the watchdog timing
capacitor. The two watchdog times are selected by choosing which
voltage to switch at. Digital input is via IC3 and output is from IC2.
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Section 5. Circuit Description
Page 23
J278 PCSYSCON
J278 PCSYSCON2192-09065-000-000
Section 5. Circuit Description
Page 24
2192-09065-000-000J278 PCSYSCON
Installation for CE Compliance
Page 25
Installation for CE Compliance
To maintain compliance with the requirements of the EMC directive
(89/336/EEC), this product must be correctly installed. The PC in
which the board is housed must be CE compliant as declared by the
PC manufacturer. The type of external I/O cable can be chosen
according to the note below:
1. Remove the cover of the PC observing any additional instructions
of the PC manufacturer.
2. Locate the board in a spare ISA slot and press gently but firmly
into place.
3. Ensure that the metal bracket attached to the board is fully seated.
4. Fit the bracket clamping screw and firmly tighten this on the
bracket.
NOTE: Good contact of the bracket to chassis is essential.
5. Replace the cover of the PC observing any additional instructions
of the PC manufacturer.
Cable
• Cable length 1 Metre of less :
Ribbon cable satisfactory
• Cable length up to 1M to 3M required :
Commercial screened cable gives the protection
• Longer cable or noisy environment :
Use fully screened cable with metal backshells e.g. Arcom CAB50CE
The following standards have been applied to this product:
BS EN50081-1: 1992 Generic Emissions Standard, Residential,
Commercial, Light Industry
BS EN50082-1: 1992 Generic Immunity Standard, Residential,
Commercial, Light Industry
BS EN55022: 1995 ITE Emissions, ClassB, Limits and Methods
J278 PCSYSCON2192-09065-000-000
Installation for CE Compliance
Page 26
2192-09065-000-000J278 PCSYSCON
Appendix A. Specification
Page 27
Appendix A. Specification
Operating temperature 0°C to 55°C
Power consumption 5V +/- 0.25V 520mA typical
Monitors +5V, +12V, -12V supplies
board temperature
two analogue inputs 0-20V
two optoisolated digital inputs 12-24V
Digital inputs 8
Digital outputs 8
Interrupt outputs to PC 3
Relay Contacts 24v 1A
Input and output levels TTL
Connectors 50-way D socket
two 10-way internal headers
Diagnostics Red and green LEDs
Board identification byte 80(H)
PCbus I/O address
space 2 bytes
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Appendix A. Specification
Page 28
2192-09065-000-000J278 PCSYSCON
Appendix B. Connections
Page 29
Appendix B. Connections
Connections are made by a 50-way D socket on the PCSYSCON. It
is most likely that you will be connecting to it via a ribbon-cable (IDC)
50-way D header plug. This can then be connected on the ribbon
cable to one or more standard (two row) 50-way headers which will
plug into the connectors on signal-conditioning boards. The diagram
shows the connections as they appear on standard ribbon-cable
headers, with the conventional D connector pin numbers given as
well as the wire numbers on the ribbon cable. The D connector pin
numbers start with D and the ribbon-cable wire numbers start with
RC. The digital I/O signals are referred to as Gn.x where n is the
group number and x is the bit number.
PL2 50-way D Connector
Signal Title D Type No. RC No
+5V 50 50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
17
33
49
16
32
48
15
31
47
14
30
46
13
29
45
12
28
44
11
27
43
10
26
42
9
25
41
8
24
40
7
23
39
+5V
+12V
-12V
Relay n/c contact
Relay com contact
Relay n/o contact
0V
Opt2 analogue input
0V
Opt 1 analogue input
0V
Opt2 optoisolated +ve input
Opt2 optoisolated -ve input
Opt1 optoisolated +ve input
Opt1optoisolated -ve input
0V
/BUZZ output
/+12V low output
/-12V low output
/+5V low output
/Opt2 output
/Opt1 output
/Watchdog output
/Overtemperature Output
0V
G1.7 in
G1.6 in
G1.5 in
G1.4 in
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Appendix B. Connections
Page 30
PL2 50-Way D Connector Continued
PL3 Internal I/O Connector
PL4 Internal I/O Connector
Signal Title D Type No. RC No
G1.3 in 6 16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
22
38
5
21
37
4
20
36
3
19
35
2
18
34
1
G1.2 in
G1.1 in
G1.0 in
0V
G0.7 out
G0.6 out
G0.5 out
G0.4 out
G0.3 out
G0.2 out
G0.1 out
G0.0 out
0V
0V
Signal Title Pin No.
+5V 10
9
8
7
6
5
4
3
2
1
/BUZZ output
/+12V low output
/-12V low output
/+5V low output
/Opt2 output
/Opt1 output
/Watchdog output
/Overtemperature output
0V
Signal Title Pin No.
+12V 10
9
8
7
6
5
4
3
2
1
Opt2 analogue input
0V
Opt1 analogue input
0V
Opt2 optoisolated +ve input
Opt2 optoisolated -ve input
Opt1 optoisolated +ve input
Opt1 optoisolated -ve input
0V
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Appendix C. Component List
Page 31
Appendix C. Component List
IC1 PC829
IC2 HCT374
IC3,9,2224 LS244
IC4 HCT240
IC5 LS245
IC6,10-12 HCT174
IC8 PAL
IC13,19 HCT138
IC14 HCT367
IC16-18 PAL
IC20 PAL
IC21 HCT688
IC22,25 HCT00
IC26,33 LM339
IC27 ACT05
IC28 LM35
IC29 LM358
IC30 LM385
IC31 8408
IC32 78L05
R1,2,12,28 680R
R3,4,4 83K
R5,8,21,24-27,29 100K
R6,14 82K
R7 1M0
R9,17,34,42,47,49 5K6
RP1 100K
VR1,2 20K
TR1-3 2N7000
TR4 BC182
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Appendix C. Component List
Page 32
Appendix D. Circuit Diagrams
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Appendix D. Circuit Diagrams
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J278 PCSYSCON
J278 PCSYSCON2192-09065-000-000
Appendix D. Circuit Diagrams
Page 34
2192-09065-000-000J278 PCSYSCON
Appendix D. Circuit Diagrams
Page 35
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J278 PCSYSCON