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5 ELC-CARS485
ELC-CARS485 is a serial Modbus distributed I/O adapter module which uses the standard low
cost ELC I/O. As a standard Modbus slave, ELC-CARS485 is compatible with any valid master.
5.1 Features
z Supports up to 256 digital I/O points
z Supports up to 8 analog / specialty modules
z Configurable interface parameters
5.2 Specification
Functions Specification
Communication
Transmission method RS-485
Electrical isolation 500VDC
Type Removable 3-pin connector
Transmission cable 2 twisted isolation cables
Valid communication
address 1 ~ F0 (decimal: 1 ~ 240)
Series transmission
speed
1,200/2,400/4,800/9,600/19,200/38,400/57,600/115,200 bps
(bits per second)
Communication mode
7,E,1-ASCII / 7,O,1-ASCII / 7,E,2-ASCII / 7,O,2-ASCII /
7,N,2-ASCII / 8,E,1-ASCII / 8,O,1-ASCII / 8,N,1-ASCII /
8,N,2-ASCII / 8,E,1-RTU / 8,O,1-RTU / 8,N,1-RTU/ 8,N,2-RTU
Electrical Specification
Power supply voltage 24VDC (-15% ~ 20%) (with DC input polarity reverse
protection)
Noise Immunity
ESD (IEC 61131-2, IEC 61000-4-2): 8KV Air Discharge, 4KV
Contact Discharge
EFT (IEC 61131-2, IEC 61000-4-4): Power Li4ne: 2KV, Digital
I/O: 1KV
Analog & Communication I/O: 1KV
Damped-Oscillatory Wave: Power Line: 1KV, Digital I/O: 1KV
RS (IEC 61131-2, IEC 61000-4-3): 80MHz ~ 1000MHz ,
1.4GHz ~ 2.0GHz , 10V/m
Operation/storage
temperature
Operation: 0°C ~ 55°C (temperature), 50 ~ 95% (humidity),
pollution degree 2;
Storage: -25°C ~ 70°C (temperature), 5 ~ 95% (humidity)
Vibration/Shock
Immunity
Standard: IEC61131-2, IEC 68-2-6 (TEST Fc)/IEC61131-2 &
IEC 68-2-27 (TEST Ea)
Certificates , Operating temperature code: T5
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5.3 Product Profile and Outline
SG D- D+
STOP
RUN
ELC-CARS485
RUN
ALARM
POWER
RS-485
1
2
3
5
6
9
8
7
4
10
11
12
13
14
15
16
1. POWER indicator 9. Mounting hole for extension unit
2. RUN indicator 10. Nameplate
3. ALARM indicator 11. Extension port for extension unit
4. RUN/STOP switch 12. DIN rail mounting slot (35mm)
5. RS485 indicator 13. Fastening hole for extension unit
6. Address setup DIP switch 14. DIN rail clip
7. Communication mode setup DIP switch 15. Mounting rail for extension unit
8. RS-485 communication port 16. Power input
Dimension
SG D- D+
STOP
RUN
RUN
ALARM
POWER
RS-485
60
90
3
3
25.2
ELC-CARS485
Unit: mm
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5.4 Installation and Wiring
Switch Definition : RUN/STOP
Status Explanation
RUN 1. RUN indicator on ELC-CARS485 is On.
2. AI/AO extension unit in RUN status.
RUN Æ STOP
1. AI/AO extension unit switches from RUN to STOP
status.
2. Y points on DI/DO extension unit are all Off.
STOP
1. RUN indicator on ELC-CARS485 is Off.
2. AI/AO extension unit in STOP status.
3. Communication control is not allowed in AI/AO
extension unit.
4. Communication control is not allowed in DI/DO
extension unit.
STOP
RUN
STOP Æ RUN
1. ELC-CARS485 re-detects the number of points in
DI/DO unit and the number of AI/AO units.
2. AI/AO extension unit switches from STOP to RUN
status.
Modbus Address Setup DIP Switch:
DIP Switch
Setting Explanation
H’01 ~ H’F0
Valid ELC-CARS485 addresses, the dip
switches are weighted as follows: ID0 ~ ID7
are: 20, 21, 22, … 26 , 27 .
H’00, H’F1 ~
H’FF
In the Modbus protocol, H’00 is defined as
broadcast mode. H’F1 ~ H’FF are incorrect
ELC-CARS485 addresses.
Communication Mode Setup DIP Switch:
PA3 PA2 PA1 PA0 A/R Communication mode
OFF OFF OFF OFF ON 7,E,1-ASCII
OFF OFF OFF ON ON 7,O,1-ASCII
OFF OFF ON OFF ON 7,E,2-ASCII
OFF OFF ON ON ON 7,O,2-ASCII
OFF ON OFF OFF ON 7,N,2-ASCII
OFF ON OFF ON ON 8,E,1-ASCII
OFF ON ON OFF ON 8,O,1-ASCII
OFF ON ON ON ON 8,N,1-ASCII
ON OFF OFF OFF ON 8,N,2-ASCII
OFF ON OFF ON OFF 8,E,1-RTU
OFF ON ON OFF OFF 8,O,1-RTU
OFF ON ON ON OFF 8,N,1-RTU
ON OFF OFF OFF OFF 8,N,2-RTU
Other settings of PA3, PA2, PA1, PA0 and A/R are invalid
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DR2 DR1 DR0 Series Transmission speed
OFF OFF OFF 1,200 bit/s
OFF OFF ON 2,400 bit/s
OFF ON OFF 4,800 bit/s
OFF ON ON 9,600 bit/s
ON OFF OFF 19,200 bit/s
ON OFF ON 38,400 bit/s
ON ON OFF 57,600 bit/s
ON ON ON 115,200 bit/s
5.5 Modbus Register assignments
Discrete Input and Outp ut register mapping
Communication
address Devices Attribute Data type Length
H’0400 ~ H’047F X: X000 ~ X177 (Octal) R bit 128 points
H’0500 ~ H’057F Y: Y000 ~ Y177 (Octal) R/W bit 128 points
Specialty Module register mapping
Communication
address Devices Attribute Data
type Length
H’1600 ~ H’1630 1st specialty module: CR0 ~ CR48 word 49
H’1640 ~ H’1670 2nd specialty module: CR0 ~ CR48 word 49
H’1680 ~ H’16B0 3rd specialty module: CR0 ~ CR48 word 49
H’16C0 ~ H’16F0 4th specialty module: CR0 ~ CR48 word 49
H’1700 ~ H’1730 5th specialty module: CR0 ~ CR48 word 49
H’1740 ~ H’1770 6th specialty module: CR0 ~ CR48 word 49
H’1780 ~ H’17B0 7th specialty module: CR0 ~ CR48 word 49
H’17C0 ~ H’17F0 8th specialty module: CR0 ~ CR48
Please refer
to the CR
attribute of
each
specialty
module.
word 49
Note:
A maximum of 8 specialty modules are allowed. The first specialty module is first unit
installed on the right hand side of the ELC-CARS485 adapter.
Adapter configura tion and status registers
Communication
address Attribute Content Explanation
H’0000 R Model name
Model code of the ELC-CARS485 =
H’0200.
H’0001 R Firmware version
The current firmware version is
displayed in hex, e.g. V0.1 is
indicated as H’0010.
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Communication
address Attribute Content Explanation
H’0002 R Issue date
The issue data of the firmware is
displayed in hex, e.g. H’1FD0 =
K8150 indicates that the firmware is
issued on the morning of August 15.
H’0003 R/W
RUN/STOP
ELC-CARS485
H’0003 = 1, the ELC-CARS485
RUN;
H’0003 = 0, the ELC-CARS485
STOP.
H’0004 R
Communication
format
The communication parameters for
the ELC-CARS485.
H’0005 R Baud rate The baud rate of the
ELC-CARS485.
H’0006 R
Communication
address
The communication address of
ELC-CARS485.
H’0007 R
Number of DI/DO
points
High byte stores the number of input
points. Low byte stores the number
of output points.
H’0008 R Error code The current error. See 4.4 for the
meaning of error codes.
H’0009 R Historical error code
The number of errors that have
occurred.
Range: 0 ~ 32
H’0017 R
Number of specialty
modules
The number of specialty modules
detected.
H’0018 R
Model code of the
1st specialty module
The model code of the 1st specialty
module connected to the
ELC-CARS485.
H’0019 R
Model code of the
2nd specialty
module
The model code of the 2nd specialty
module connected to the
ELC-CARS485.
H’001A R
Model code of the
3rd specialty module
The model code of the 3rd specialty
module connected to the
ELC-CARS485.
H’001B R
Model code of the
4th specialty module
The model code of the 4th specialty
module connected to the
ELC-CARS485.
H’001C R
Model code of the
5th specialty module
The model code of the 5th specialty
module connected to the
ELC-CARS485.
H’001D R
Model code of the
6th specialty module
The model code of the 6th specialty
module connected to the
ELC-CARS485.
H’001E R
Model code of the
7th specialty module
The model code of the 7th specialty
module connected to the
ELC-CARS485.
H’001F R
Model code of the
8th specialty module
The model code of the 8th specialty
module connected to the
ELC-CARS485.
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5.6 Supported Function Codes
ELC-CARS485 complies with the standard Modbus protocol, supporting the 7 function codes,
H’01, H’02, H’03, H’05, H’06, H’0F, and H’10. Please refer to the standard Modbus protocol for
the specific data format of each function code.
Function
code Function Data type Applicable address
H’01 Read output bit status bit DO area: H’0500 ~ H’057F
H’02 Read input bit status. bit DI area: H’0400 ~ H’047F
Special function area: H’0000 ~ H’001F
CR of the 1st AI/AO unit: H’1600 ~ H’1630
CR of the 2nd AI/AO unit: H’1640 ~ H’1670
CR of the 3rd AI/AO unit: H’1680 ~ H’16B0
CR of the 4th AI/AO unit: H’16C0 ~ H’16F0
CR of the 5th AI/AO unit: H’1700 ~ H’1730
CR of the 6th AI/AO unit: H’1740 ~ H’1770
H’03 Read register(s) word
CR of the 7th AI/AO unit: H’1780 ~ H’17B0
H’03 Read register(s) word CR of the 8th AI/AO unit: H’17C0 ~ H’17F0
H’05 Write single bit bit DO area: H’0500 ~ H’057F
RUN/STOP ELC-CARS485 module: H’0003
H’06 Write single register word Applicable to CR with write attribute in the
1st ~ 8th AI/AO extension unit.
H’0F Write multiple bits bit DO area: H’0500 ~ H’057F
RUN/STOP ELC-CARS485 module: H’0003
H’10 Write multiple
registers word Applicable to CR with write attribute in the
1st ~ 8th AI/AO extension unit.
Example:
z Use function code 03 to read CR0 and CR1 in the 1st AI/AO extension unit: (ASCII
mode)
z The request message sent from master ELC to ELC-CARS485 is “: 01 03 16 00 00 02
E4 CR LF”
z The responding message sent from ELC-CARS485 to the master ELC is “: 01 03 04 00
88 00 00 70 CR LF”
Note:
1. ELC-CARS485 can only read and write one AI/AO extension unit at a time.
2. ELC-CARS485 is able to read/write a maximum of 16 words at a time.
z Error Codes
Code Indication Explanation
0001 Incorrect function code The ELC-CARS485 does not support this
function code.
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Code Indication Explanation
0002 Incorrect operand address The function code is not valid for the
operand address
0003 Incorrect data The data read/written exceeds the
maximum length.
0004 The ELC-CARS485 in STOP The ELC-CARS485 is in STOP mode.
000B Incorrect communication
format
The length of data received by the
ELC-CARS485 is too short.
000C Incorrect communication
format
The length of data received by the
ELC-CARS485 is too long.
5.7 Application example: ELC processor as the Modbus master
As a Modbus slave, the ELC-CARS485 is compatible with any valid Modbus master. This
example uses an ELC controller as the Modbus master. The PC downloads the ladder program
to the ELC controller via the RS-232 programming port (COM1). When controller executes the
ladder program, it will issue Modbus commands through the RS-485 communication port
(COM2), monitoring inputs and controlling outputs through the ELC-CARS485 adapter. See the
figure below for the system overview:
ELC-EX16NNDR
ELC-AN06AANN
ELC-CARS485
RS485
COM2
ELC-CARS485 DI/DO AI/AO
ELC-PV28NNDR
ELC-EX16NNDR
The station No. of the ELC-CARS485 is node “2”. The master ELC-PV controller is node 1.
Read the state of “X0 ~ X15” with the ELC-PV controller from the ELC-CARS485. Also, write to
control outputs “Y0 ~ Y7” in the first ELC-EX16NNDR. Then write the value from “D500 ~ D501”
in the ELC-PV controller to “CR10 ~ CR11” in the ELC-AN06AANN module. Finally, read the
values in “CR6 ~ CR9” in ELC-AN06AANN.
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Explanations:
(1) Set up the communication parameters at the beginning of the program, conditioned with
the power-up bit. The communication parameters for the master and slave must be the
same, e.g. both devices must be configured form the same baud rate, bits/byte, parity,
stop bits and RTU/ASCII mode. Each device must also have a unique node address. For
this example, each device is configured for: 115200 baud, 8 bits/byte, Even parity, 1 stop
bit and RTU mode.
(2) When the ELC controller transitions to run mode, the value of “D0” will be initialized to “0”.
(3) When the value of “D0” is “0”, the ELC controller will read the state of “X0 ~ X15” (H400 –
H40F) in the ELC extension modules and save it in “D220”.
(4) When the value of “D0” is “1”, the ELC controller will write to “Y0 ~ Y7” with the data in the
low byte of “D400”.
(5) When the value of “D0” is “2”, the ELC controller will write the values in “D500~D501” to
“CR10~CR11” in the 1st special module (ELC-AN06 for this example).
(6) When the value of “D0” is “3”, the ELC controller will read the values from “CR6 ~ CR9” in
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the special module (ELC-AN06) and buffer it in “D200 ~ D203”. The Modbus reply header
information will be written to D550-D553.
(7) When the value of “D0” is “4”, and the fourth message has been executed, the ELC
controller will re-initialize the value of “D0” to K0, to begin the message cycle again.
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MEMO
