RKC INSTRUMENT CB900 Instruction manual

Digital Controller
CB100/CB400
CB500/CB700
CB900
[Z-1021]
MODBUS
Communication
Instruction Manual
®
RKC INSTRUMENT INC.
IMCB14-E1
z
Modbus is a registered trademark of Schneider Electric.
z
Company names and product names used in this manual are the trademarks or registered trademarks of
the respective companies.
All Rights Reserved, Copyright ¤ 1999, RKC INSTRUMENT INC.
Thank you for purchasing the RKC instrument. In order to achieve maximum performance and ensure
proper operation of your new instrument, carefully read all the instructions in this manual. Please
place this manual in a convenient location for easy reference.
SYMBOLS
WARNING
: This mark indicates precautions that must be taken if there is danger of electric
shock, fire, etc., which could result in loss of life or injury.
CAUTION
: This mark indicates that if these precautions and operating procedures are not
taken, damage to the instrument may result.
!
: This mark indicates that all precautions should be taken for safe usage.
: This mark indicates important information on installation, handling and operating
procedures.
: This mark indicates supplemental information on installation, handling and
operating procedures.
: This mark indicates where additional information may be located.
!
WARNING
An external protection device must be installed if failure of this instrument
z
could result in damage to the instrument, equipment or injury to personnel.
All wiring must be completed before power is turned on to prevent electric
z
shock, fire or damage to instrument and equipment.
This instrument must be used in accordance with the specifications to prevent
z
fire or damage to instrument and equipment.
This instrument is not intended for use in locations subject to flammable or
z
explosive gases.
Do not touch high-voltage connections such as power supply terminals, etc.
z
to avoid electric shock.
RKC is not responsible if this instrument is repaired, modified or
z
disassembled by other than factory-approved personnel. Malfunction can
occur and warranty is void under these conditions.
IMCB14-E1
i-1
CAUTION
z This is a Class A instrument. In a domestic environment, this instrument may cause radio
interference, in which case the user may be required to take adequate measures.
z This instrument is protected from electric shock by reinforced insulation. Provide
reinforced insulation between the wire for the input signal and the wires for instrument
power supply, source of power and loads.
z This instrument is designed for installation in an enclosed instrumentation panel. All highvoltage connections such as power supply terminals must be enclosed in the
instrumentation panel to avoid electric shock by operating personnel.
z All precautions described in this manual should be taken to avoid damage to the
instrument or equipment.
z All wiring must be in accordance with local codes and regulations.
z To prevent instrument damage or failure, protect the power line and the input/output lines
from high currents with a protection device such as fuse, circuit breaker, etc.
z Prevent metal fragments or lead wire scraps from falling inside instrument case to avoid
electric shock, fire or malfunction.
z Tighten each terminal screw to the specified torque found in the manual to avoid electric
shock, fire or malfunction.
z For proper operation of this instrument, provide adequate ventilation for heat dispensation.
z Do not connect wires to unused terminals as this will interfere with proper operation of the
instrument.
z Turn off the power supply before cleaning the instrument.
z Do not use a volatile solvent such as paint thinner to clean the instrument. Deformation or
discoloration will occur. Use a soft, dry cloth to remove stains from the instrument.
z To avoid damage to instrument display, do not rub with an abrasive material or push front
panel with a hard object.
NOTICE
z This manual assumes that the reader has a fundamental knowledge of the principles of electricity,
process control, computer technology and communications.
z The figures, diagrams and numeric values used in this manual are only for purpose of illustration.
z RKC is not responsible for any damage or injury that is caused as a result of using this instrument,
instrument failure or indirect damage.
z Periodic maintenance is required for safe and proper operation of this instrument. Some
components have a limited service life, or characteristics that change over time.
z Every effort has been made to ensure accuracy of all information contained herein. RKC makes no
warranty expressed or implied, with respect to the accuracy of the information. The information in
this manual is subject to change without prior notice.
z No portion of this document may be reprinted, modified, copied, transmitted, digitized, stored,
processed or retrieved through any mechanical, electronic, optical or other means without prior
written approval from RKC.
i-2
IMCB14-E1
CONTENTS
Page
1. OUTLINE ..............................................................................1
2. SPECIFICATIONS ................................................................2
3. WIRING.................................................................................3
4. COMMUNICATION SETTINGS............................................6
4.1
4.2
4.3
4.4
4.5
4.6
4.7
Communication Setting Mode .........................................................................6
Select Communication Parameters.................................................................7
Slave Address Setting .....................................................................................8
Communication Speed Setting......................................................................10
Data Configuration Setting ............................................................................12
Interval Time Setting .....................................................................................14
RS-485 Send/Receive Process Timing .........................................................17
5. MODBUS PROTOCOL.......................................................18
5.1
5.2
5.3
5.4
5.5
Message Format ...........................................................................................18
Function Code ...............................................................................................19
Communication Mode ...................................................................................19
Slave Response ............................................................................................20
Calculating CRC-16.......................................................................................21
6. MESSAGE FORMAT..........................................................23
6.1 Read Holding Registers [03H] .......................................................................23
6.2 Preset Single Registers [06H] .......................................................................24
6.3 Diagnostics (loopback test) [08H]..................................................................25
IMCB14-E1
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Page
7. DATA CONFIGURATION....................................................26
7.1 Data Configuration ........................................................................................26
7.2 Data Processing Precautions ........................................................................27
7.3 Communication Data List ..............................................................................28
8. TROUBLESHOOTING .......................................................35
i-4
IMCB14-E1
1. OUTLINE
This manual describes the specifications, wiring instructions and communication settings for
CB100/CB400/CB500/CB700/CB900 Z-1021 with Modbus communication protocol.
Slave side
RS-485
MODBUS
Host computer
or PLC etc.
or
BRA-100B-2
Master side
MODBUS
CB100/CB400/CB500
CB700/CB900
(Slave address 1)
MODBUS
CB100/CB400/CB500
CB700/CB900
(Slave address 2)
MODBUS
CB100/CB400/CB500
CB700/CB900
(Slave address 3)
MODBUS
CB100/CB400/CB500
CB700/CB900
(Slave address 4)
RS-232C
MODBUS
RS-232C/RS-485
converter
BRA-100-2
Host computer
or PLC etc.
Junction
branch box
CB100/CB400/CB500
CB700/CB900
(Slave address 31)
IMCB14-E1
1
2. SPECIFICATIONS
(1) Interface:
Based on RS-485, EIA standard
(2) Connection method:
2-wire system, half-duplex multi-drop connection
(3) Protocol:
Modbus
(4) Signal transmission mode: Remote Terminal Unit (RTU) mode
(5) Synchronous method:
Start/stop synchronous type
(6) Communication speed:
2400 bps, 4800 bps, 9600 bps, 19200 bps
(Selectable)
(7) Data type:
Data bit:
8 (Byte data corresponding to binary data or
bit)
Parity check : Without, Odd or Even (Selectable)
Stop bit:
1
(8) Function codes:
03H (Read holding registers)
06H (Preset single register)
08H Diagnostics (loopback test)
(9) Error check method:
CRC-16
(10) Error codes:
1: Function code error
(Designation of an unsupported function code)
2: When written to read only data
When any address other than 0000H to 0019H is
specified, etc.
3: When the data written exceeds the setting range
When the specified number of data items in the query
message exceeds the maximum number of data items
available
4: Self-diagnostic error response
(11) Maximum connection: 32 instruments including a master
2
IMCB14-E1
3. WIRING
!
WARNING
To prevent electric shock or instrument failure, turn off the power before
connecting or disconnecting the instrument and peripheral equipment.
Terminal number and signal details
„
CB100/CB400/CB500/CB900
Terminal No.
Signal name
Name
13
SG
14
T/R(A)
Send data/Receive data
15
T/R(B)
Send data/Receive data
Terminal No.
Signal name
7
SG
8
T/R(A)
Send data/Receive data
9
T/R(B)
Send data/Receive data
Slave
Signal direction
Master
Slave
Signal direction
Master
Signal ground
CB700
IMCB14-E1
Name
Signal ground
3
3. WIRING
Connection to the RS-485 port of the master
„
The master has a built-in circuit to transfer send/receive data alternatively.
RS-485
Paired wire
Master
SG
T/R(A)
SG
T/R(A)
T/R(B)
T/R(B)
Slave
y
y
y
RD (RXD):Receive data
Send/Receive
transfer signal
Shielded twisted
pair wire
SG
SD (TXD):Send data
SD (TXD) and RD (RXD): Negative logic
T/R(A)
T/R(B)
Slave
(31 max.)
Use a terminal resistor with a combined resistance of 100 : on the last controller.
Connection to the RS-232C port of the master
„
A RS-232C/RS-485 communication converter is requited.
Paired wire
RS-485
SG
SG
T/R(A)
T/R(A)
T/R(B)
T/R(B)
RS-232C
Slave
Shielded twisted
pair wire
RS-232C/RS-485
converter
Master
Use a terminal resistor with a combined resistance of 100 : on the last controller.
When the master uses Windows 95/NT, use a RS-232C/RS-485 converter with an automatic
send/receive transfer function.
Recommended: CD485, CD485/V manufactured by Data Link, Inc. or equivalent.
4
IMCB14-E1
3. WIRING
Connection with up to 31 slaves and one master
„
Master
Master
RS-232C
RS-485
RS-232C/RS-485 converter
RS-485
or
BRA-100B-2
BRA-100B-2
BRA-100B-2
RS-485
Slave address
example
1
2
Slaves
3
4
Slaves
29
30
31
Slaves
For all pertinent details on the RS-232C/RS-485 converter and junction branch box (BRA100B-2), see the respective instruction manuals.
IMCB14-E1
5
4. COMMUNICATION SETTINGS
To establish communication parameters between master and slave, it is necessary to set the slave
address, communication speed, data configuration and interval time on each slave in the
communication mode.
The CB900 controller will be used as an example, but the same instructions apply to all CB Series
controllers with Modbus protocol.
4.1 Communication Setting Mode
1. When the power to the instrument is turned on, the input type, input range and PV/SV display
mode will be automatically displayed in that order.
2. To go to the communication setting mode, you must be in either PV/SV display mode or the SV
setting mode. Press and hold the SET key and press the <R/S key at the same time to initiate
communication settings. The first parameter to be displayed will be the slave address, Add.
PV
PV
SV
SV
AT OUT1 OUT2 ALM1 ALM2
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
PV/SV display mode
SET
R/S
Communication setting mode
Add -Slave address setting
The number segment being set will
be brighter than the others in the
SV display
To return to the PV/SV display mode, press and hold the SET key and press the <R/S key at
the same time.
6
IMCB14-E1
4. COMMUNICATION SETTINGS
4.2 Select Communication Parameters
To select parameters in communication setting mode, press the SET key. The parameters are
displayed and sequenced in the order of slave address, Add, communication speed, bPS, data
configuration, bIT and interval time set value, InT.
Display flowchart
„
Power On
Input type and input range
display
Display changes automatically
PV/SV display mode
(Display for approx. 4 sec)
Press the
SET key.
SV setting mode
Press and hold the SET key and press the
<R/S key at same time.
Communication setting mode
PV
Slave address
(Add)
SV
Press the SET key.
PV
Communication speed
(bPS)
PV/SV display
mode
SV
Press the SET key.
PV
Data configuration
(bIT)
Press and hold the
SET key and press
the <R/S key at
same time.
SV
Press the SET key.
PV
Press the
SET key.
IMCB14-E1
Interval time set value
(InT)
SV
7
4. COMMUNICATION SETTINGS
4.3 Slave Address Setting
The slave address must be set before Modbus communication can begin. The slave address number
is set with numbers from 1 to 99. The factory set value is 0 and two-way communication is not
possible when the address is 0.
Symbol
Name
Slave address
Setting range
1 to 99*
Description
Set the controller slave
address.
Factory set
value
0
Add
* Two-way communication is not possible when the address is 0.
When the communication parameter is changed, turn the power on and off again to refresh and
make the new value effective.
All slave address settings must be stored by pressing the SET key. If changes are made and
the SET key is not pressed within one minute, the display will automatically return to the
PV/SV display mode and the slave address will return to the value prior to set change.
Setting procedure
„
Example:
Setting the slave address to 15
1. Go to the communication setting mode so that slave address, Add, is displayed.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
Slave address
8
IMCB14-E1
4. COMMUNICATION SETTINGS
2. Press the UP key to enter 5 at the first digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
3. Press the <R/S key to high-light the second digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
4. Press the UP key to enter 1 at the second digit form the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
5. Press the SET key to store the new slave address. The display automatically goes to the next
communication parameter, bPS.
IMCB14-E1
9
4. COMMUNICATION SETTINGS
4.4 Communication Speed Setting
The communication speed of 2400bps, 4800bps, 9600bps or 19200bps is set with numbers from 0 to 3.
To change the number of the digit, press the UP or DOWN key.
Symbol
Name
Communication
speed
bPS
Setting range
0 : 2400 bps
1 : 4800 bps
2 : 9600 bps
3 : 19200 bps
Description
Select the communication
speed
Factory set
value
2
Set the same communication speed for both the slave and the master.
When the communication parameter is changed, turn the power on and off again to refresh and
make the new value effective.
All communication speed settings must be stored by pressing the SET key. If changes are
made and the SET key is not pressed within one minute, the display will automatically return
to the PV/SV display mode and the communication speed will return to the value prior to set
change.
Setting procedure
„
Example:
Setting the communication speed to 1:
4800 bps
1. Go to the communication setting mode so that slave address, Add, is displayed.
SET key once, so the communication speed symbol, bPS, appears.
Then, press the
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
Communication speed
10
IMCB14-E1
4. SETTING FOR COMMUNICATION
2. Press the DOWN key to enter 1 (4800 bps) at the first digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
3. Press the SET key to store the new communication speed.
the next communication parameter, bIT.
IMCB14-E1
The display automatically goes to
11
4. SETTING FOR COMMUNICATION
4.5 Data Configuration Setting
The data configuration shown below is set with numbers from 1 to 3.
digit, press the UP or DOWN key.
Symbol
Name
Data
configuration
bIT
Setting range
0, 6 or 7
See Data
To change the number of the
Description
Select data configuration
during communication
Factory set
value
0
Configuration
Table
Data configuration table
Setting
Data bit
0
8
1 to 5
Parity bit
Stop bit
None
1
Do not set 1 to 5. Malfunction may result.
6
8
Even
1
7
8
Odd
1
Set the same data configuration for both the slave and the master.
When the communication parameter is changed, turn the power on and off again to refresh and
make the new value effective.
All data configuration settings must be stored by pressing the SET key. If changes are made
and the SET key is not pressed within one minute, the display will automatically return to the
PV/SV display mode and the data configuration will return to the value prior to set change.
12
IMCB14-E1
4. SETTING FOR COMMUNICATION
Setting procedure
„
Example:
Setting the data configuration to 6: 8 data bits, even parity and 1 stop bit.
1. Go to the communication setting mode so that slave address, Add, is displayed.
key until the data configuration symbol, bIT, appears.
Press the SET
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
Data configuration
2. Press the UP key to enter 6 at the first digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
3. Press the SET key to store the new data configuration. The display automatically goes to the next
communication parameter, InT.
IMCB14-E1
13
4. SETTING FOR COMMUNICATION
4.6 Interval Time Setting
The interval time from 0 to 250 ms is set with numbers from 0 to 150. To shift the digit, press the
<R/S key. To change the number of the digit, press the UP or DOWN key.
Symbol
Name
Interval time set
value
Setting range
0 to 150*
Description
Set the value to set the interval
time
Factory set
value
5
InT
* 0 to 250 ms can be set by using 0 to 150.
Formula to calculate interval time and interval time set value
Interval time = Interval time set value u 1.666 ms
Interval time set value = Interval time y 1.666 ms
When the communication parameter is changed, turn the power on and off again to refresh and
make the new value effective.
All interval times must be stored by pressing the SET key. If changes are made and the SET
key is not pressed within one minute, the display will automatically return to the PV/SV
display mode and the interval time will return to the value prior to set change.
Setting procedure
„
Example:
Setting the interval time to 250 ms.
1. Go to the communication setting mode so that slave address, Add, is displayed.
key until the communication speed, InT, appears.
Press the SET
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
Interval time set value
14
IMCB14-E1
4. SETTING FOR COMMUNICATION
2. Calculate the interval time set value by using the formula on the previous page. The interval
time set value must be a whole number. If you get a number with a decimal fraction, round to
the nearest whole number.
Interval time set value:
250 ms y 1.666 ms 150 (Round to the nearest whole number)
The actual interval time re-calculated by using the interval time set value, 150:
150 u 1.666 ms 249.9 (Approx. 250 ms)
Enter an interval time set value of 150, calculated as show above, on the controller.
3. Press the DOWN key to enter 0 at the first digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
4. Press the <R/S key to high-light the second digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
IMCB14-E1
R/S
15
4. SETTING FOR COMMUNICATION
5. Press the UP key to enter 5 at the second digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
6. Press the <R/S key to high-light the third digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
7. Press the UP key to enter 1 at the third digit from the right.
PV
SV
AT OUT1 OUT2 ALM1 ALM2
SET
R/S
8. Press the SET key to store the new interval time.
communication parameter, Add.
16
The display automatically goes back to the
IMCB14-E1
4. SETTING FOR COMMUNICATION
4.7 RS-485 Send/Receive Process Timing
The sending and receiving of RS-485 communication is conducted through two wires; consequently,
the transmission and reception of data requires precise timing. The following processing times are
required during data send/receive.
Slave process timing
Procedure details
Read holding registers [03H]
IMCB14-E1
Time (ms)
Response transmission time after the
slave
receives the query message
Preset single register [06H]
13 ms max.
Response transmission time after the
slave
receives the query message
Diagnostics (loopback test) [08H]
6 ms max.
Response transmission time after the
slave
receives the query message
6 ms max.
17
5. MODBUS PROTOCOL
The master controls communication between master and slave. A typical message consists of a
request (query message) sent from the master followed by an answer (response message) from the
slave. When master begins data transmission, a set of data is sent to the slave in a fixed sequence.
When it is received, the slave decodes it, takes the necessary action, and returns data to the master.
5.1 Message Format
The message consists of four parts: slave address, function code, data, and error check code which are
always transmitted in the same sequence.
Slave address
Function code
Data
Error check CRC-16
Message format
■ Slave address
The slave address is a number from 1 to 99 manually set at the front key panel of the controller.
Although all connected slaves receive the query message sent from the master, only the slave with the
slave address coinciding with the query message will accept the message.
■ Function code
The function codes are the instructions set at the master and sent to the slave describing the action to
be executed. The function codes are included when the slave responds to the master.
For details, see 5.2 Function Code.
■ Data
The data to execute the function specified by the function code is sent to the slave and corresponding
data returned to the master from the slave.
For details, see 6. MESSAGE FORMAT, 7. DATA CONFIGURATION and 7.3 Communication
Data List.
■ Error check
An error checking code (CRC-16: Cyclic Redundancy Check) is used to detect an error in the signal
transmission. For the calculation method of CRC-16, see 5.5 Calculating CRC-16.
18
IMCB14-E1
5. MODBUS PROTOCOL
5.2 Function Code
zFunction code contents
Function code
(Hexadecimal)
Function
03H
Read holding registers
06H
Preset single register
08H
Diagnostics (loopback test)
Contents
Measured value (PV), alarm status, current
transformer input, etc.
Set value (SV), alarm set value, PID constants,
PV bias, etc. (For each word)
Diagnostics (loopback test)
zMessage length of each function (Unit: byte)
Function code
(Hexadecimal)
Function
Query message
Response message
Min
8
Max
8
Min
7
Max
255
03H
Read holding registers
06H
Preset single register
8
8
8
8
08H
Diagnostics (loopback test)
8
8
8
8
5.3 Communication Mode
Signal transmission between the master and slaves is conducted in Remote Terminal Unit (RTU)
mode.
RTU mode
Items
Data bit length
Start mark of message
End mark of message
Message length
Data time interval
Error check
Contents
8 bit (Binary)
Unused
Unused
See 5.2 Function Code
24 bit's time or less*
CRC-16
* The data time intervals in one query message from the master must be 24 bit's time or less.
If the data time interval exceeds 24 bit's time, the slave regards the transmission as ended
and because the message format is incomplete, the slave does not respond.
IMCB14-E1
19
5. MODBUS PROTOCOL
5.4 Slave Responses
(1) Normal response
zIn the response message of the Read Holding Registers, the slave returns the read out data and the
number of data items with the same slave address and function code as the query message.
zIn the response message of the Preset Single Register, the slave returns the same message as the
query message.
zIn the response message of the Diagnostics (loopback test), the slave returns the same message as
the query message.
(2) Defective message response
zIf the query message from the master is defective, except for transmission error, the slave returns
the error response message without any action.
Slave address
Function code
Error code
Error check CRC-16
Error response message
zIf the self-diagnostic function of the slave detects an error, the slave will return an error response
message to all query messages.
zThe function code of each error response message is obtained by adding 80H to the function code
of the query message.
Error code
1
2
3
4
Contents
Function code error (Designation of an unsupported function code)
When written to read only data
When any address other than 0000H to 0019H is specified
When PID constants or anti-reset windup (ARW) data are set to 0 and 1 is
entered at self-tuning (ST) function
When either one of PID constants and anti-reset windup (ARW) data are written
during execution of the self-tuning (ST) function
When the data written exceeds the setting range
When the specified number of data items in the query message exceeds the
maximum number of data items available
Self-diagnostic error response
(3) No response
The slave ignores the query message and does not respond when:
z
The slave address in the query message does not coincide with any slave address settings.
z
The transmission parameter of the master does not coincide with that of the slave.
z
Transmission error such as overrun, framing, parity and etc., is found in the query message.
z
Data time interval in the query message from the master exceeds 24 bit's time.
20
IMCB14-E1
5. MODBUS PROTOCOL
5.5 Calculating CRC-16
The Cyclic Redundancy Check (CRC) is a 2 byte (16-bit) error check code. After constructing the
data message, not including start, stop, or parity bit, the master calculates a CRC code and appends
this to the end of the message. The slave will calculate a CRC code from the received message, and
compare it with the CRC code from the master. If they do not coincide, a communication error has
occurred and the slave does not respond.
The CRC code is formed in the following sequence:
1. Load a 16-bit CRC register with FFFFH.
2. Exclusive OR (†) the first byte (8 bits) of the message with the CRC register. Return the result to
the CRC register
3. Shift the CRC register 1 bit to the right.
4. If the carry flag is 1, exclusive OR the CRC register with A001 hex and return the result to the
CRC register. If the carry flag is 0, repeat step 3.
5. Repeat step 3 and 4 until there have been 8 shifts.
6. Exclusive OR the next byte (8 bits) of the message with the CRC register..
7. Repeat step 3 through 6 for all bytes of the message (except the CRC).
8. The CRC register contains the 2 byte CRC error code. When they are appended to the message,
the low-order byte is appended first, followed by the high-order byte.
IMCB14-E1
21
5. MODBUS PROTOCOL
The flow chart of CRC-16
„
START
FFFFH o CRC Register
CRC Register † next byte of the message o
CRC Register
0on
Shift CRC Register right 1 bit
Carry flag is 1
No
Yes
CRC Register † A001H
o CRC Register
n+1on
No
n!7
Yes
No
Is message
complete ?
Yes
END
The † symbol indicates an exclusive OR operation.
The symbol for the number of data bits is n.
22
IMCB14-E1
6. MESSAGE FORMAT
6.1 Read Holding Registers [03H]
The query message specifies the starting register address and quantity of registers to be read.
The contents of the holding registers are entered in the response message as data, divided into two
parts: the high-order 8 bits and the low-order 8 bits, arranged in the order of the register numbers.
Example: The contents of the three holding registers from 0000H to 0002H are the read out from
slave address 2.
Query message
Slave address
Function code
Starting number
Quantity
CRC-16
High
Low
High
Low
High
Low
02H
03H
00H
00H
00H
03H
05H
F8H
First holding register address
The setting must be between 1 and 125
(0001H and 007DH)
Normal response message
Slave address
Function code
Number of data
First holding
register contents
Next holding
register contents
Next holding
register contents
CRC-16
High
Low
High
Low
High
Low
High
Low
02H
03H
06H
00H
64H
00H
00H
00H
00H
44H
4DH
Number of holding registers u 2
Error response message
Slave address
80H Function code
Error code
CRC-16
IMCB14-E1
High
Low
02H
83H
03H
F1H
31H
23
6. MESSAGE FORMAT
6.2 Preset Single Register [06H]
The query message specifies data to be written into the designated holding register. The write data
is arranged in the query message with high-order 8 bits first and low-order 8 bits next. Only R/W
holding registers can be specified.
Example:
Data is written into the holding register 0006H of slave address 1.
Query message
Slave address
Function code
Holding register
number
Write data
CRC-16
High
Low
High
Low
High
Low
01H
06H
00H
06H
00H
C8H
68H
5DH
Any data within the range
Normal response message
Slave address
Function code
Holding register
number
Write data
CRC-16
High
Low
High
Low
High
Low
01H
06H
00H
C6H
00H
08H
68H
5DH
Contents will be the same as query message data.
Error response message
Slave address
80H Function code
Error code
CRC-16
24
High
Low
01H
86H
02H
C3H
A1H
IMCB14-E1
6. MESSAGE FORMAT
6.3 Diagnostics (Loopback Test) [08H]
The master's query message will be returned as the response message from the slave.
checks the communication system between the master and slave.
Example:
This function
Loopback test for slave address 1
Query message
Slave address
Function code
Test code
Data
CRC-16
High
Low
High
Low
High
Low
01H
08H
00H
00H
1FH
34H
E9H
ECH
Test code must be set to 00
Any pertinent data
Normal response message
Slave address
Function code
Test code
Data
CRC-16
High
Low
High
Low
High
Low
01H
08H
00H
00H
1FH
34H
E9H
ECH
Contents will be the same as query message data.
Error response message
Slave address
80H Function code
Error code
CRC-16
IMCB14-E1
High
Low
01H
88H
03H
06H
01H
25
7. DATA CONFIGURATION
7.1 Data Configuration
The numeric range of data used in Modbus protocol is 0000H to FFFFH.
the setting range is effective.
Only the set value within
FFFFH represents -1.
Data processing with decimal points
■ Data with decimal points
The Modbus protocol does not recognize data with decimal points during communication.
z Data with one decimal place
Current transformer input 1
Current transformer input 2
(Z-168 specification)
Control loop break alarm
Example:
00C8H
Heater break alarm 1
Heater break alarm 2
(Z-168 specification)
When heater break alarm (HBA) 1 set value is 20.0 A; 20.0 is processed as 200, 200 =
Heater break alarm 1
High
Low
00H
C8H
■ Data without decimal points
Alarm 1 status
Alarm 2 status
Burnout
LBA deadband
Autotuning (AT)
Self-tuning (ST)
Integral time
Example:
When integral time is 50 seconds, 50 is processed as 50, 50 = 0032H
Integral time
26
Derivative time
Anti-reset windup
Heat-side proportioning cycle time
Cool-side proportional band
Cool-side proportioning cycle time
Set data lock function
RUN/STOP function
High
Low
00H
32H
IMCB14-E1
7. DATA CONFIGURATION
■ Data whose decimal point's presence and/or position depends on input
range
The position of the decimal point changes depending on the input range type because the Modbus
protocol does not recognize data with decimal points during communication.
The following data can have one of three decimal point positions:
z No decimal point
z One decimal place
z Two decimal places
The input range for voltage/current input is fixed at 0.0 to 100.0%. For details, see Input Range
Table 2 on P.34.
Measured value (PV)
Set value (SV)
Alarm 1 set value
Alarm 2 set value
Example:
Heat-side proportional band
Deadband
PV bias
When the temperature set value is -20.0 qC; -20.0 is processed as -200,
-200 = 0000H - 00C8H = FF38H
Set value (SV)
High
Low
FFH
38H
7.2 Data Processing Precautions
zFor 03H (data read from the holding register), an error response message is returned when any
address other than 0000H to 0019H is specified as the starting number.
zFor 06H (data write to the single holding register), an error response message is returned when
data is written to any address other than 0000H to 0019H.
zRead data of unused channel and undefined address is 0.
zAny attempt to write to an unused channel is not processed as an error.
into an unused channel.
Data can not be written
zIf data range or address error occurs during data writing, the data written before error is in effect.
IMCB14-E1
27
7. DATA CONFIGURATION
7.3 Communication Data List
The communication data list summarizes data addresses (holding register numbers), names, attributes,
setting ranges and factory set values.
(Attribute
Attribute
Address
Name
00H
01H
02H
03H
04H
05H
06H
07H
Measured value (PV)
Current transformer input 1
Current transformer input 2
*1
Alarm 1 status
Alarm 2 status
Burnout
Set value (SV)
Alarm 1 set value
08H
Alarm 2 set value
09H
0AH
0BH
Heater break alarm 1
Heater break alarm 2
*2
Control loop break alarm
R/W
R/W
R/W
0CH
LBA deadband
R/W
0DH
Autotuning (AT)
R/W
0EH
Self-tuning (ST)
28
*3
RO: Read only R/W: Read and Write)
Factory
Data range or item description
set value
RO
RO
RO
Within input range
0.0 to 100.0 A
0.0 to 100.0 A
RO
RO
RO
R/W
R/W
0: OFF
1: ON
0: OFF
1: ON
0: OFF
1: ON
Within input range
0
Temperature input:
Temperature
Process alarm, deviation alarm, SV input:
alarm:
50 or 50.0
-1999 to +9999 qC [qF] or
-199.9 to +999.9 qC [qF]
Voltage/current inputs:
Voltage/
Deviation alarm: -span to +span
current
(Within 9999)
inputs:
Process alarm, SV alarm:
5.0
Within input range
0.0 to 100.0 A
0.0
0.0 to 100.0 A
0.0
0.1 to 200.0 min.
8.0
(0.0 can not be set.)
Temperature input:
0
0 to 9999 qC [qF]
Voltage/current inputs:
0 to 100 % of span
0: Autotuning (AT) end or
0
suspension
1: Autotuning (AT) start*
*After AT is completed, setting will
automatically change to 0
0: Self-tuning (ST) suspension
0
1: Self-tuning (ST) start
Continued on the next page.
R/W
-
IMCB14-E1
7. DATA CONFIGURATION
Continued from the previous page.
(Attribute
Attribute
Address
Name
0FH
Heat-side proportional band
(P)
*4
R/W
10H
Integral time (I)
*4
R/W
11H
Derivative time (D)
*4
R/W
12H
Anti-reset windup (ARW)
*4
R/W
13H
Heat-side proportioning
cycle time
R/W
14H
Cool-side
band
Deadband
R/W
15H
proportional
R/W
16H
Cool-side proportioning
cycle time
R/W
17H
PV bias
R/W
IMCB14-E1
RO: Read only R/W: Read and Write)
Factory
Data range or item description
set value
Temperature input: 1 (0.1) to span or Temperature
9999 (999.9) qC [qF]
input:
Voltage/current inputs:
30 (30.0)
0.1 to 100.0 % of span
(ON/OFF action control when set to Voltage/
0 or 0.0.)
current
Can not be set while the self-tuning inputs:
(ST) function is On
3.0
1 to 3600 sec (0: PD control)
240
Can not be set while the self-tuning
(ST) function is On
1 to 3600 sec (0: PI control)
60
Can not be set while the self-tuning
(ST) function is On
1 to 100 % of heat-side proportional
100
band (0: Integral action OFF)
Can not be set while the self-tuning
(ST) function is On
1 to 100 sec (0 can not be set.)
*5
Can not be set if the control output
is current output.
1 to 1000% of heat-side proportional
100
band (0 can not be set.)
Temperature input:
0 or 0.0
-10 to +10 qC [qF] or
-10.0 to +10.0 qC [qF]
Voltage/current inputs:
-10.0 to +10.0 % of span
1 to 100 sec (0 can not be set.)
*6
Can not be set if the control output
is current output.
-span to +span
0 or 0.0
However, temperature inputs:
-1999 to +1999 qC [qF] or
-199.9 to 999.9 qC [qF]
Continued on the next page.
29
7. DATA CONFIGURATION
Continued from the previous page.
(Attribute
Address
Attribute
Name
RO: Read only R/W: Read and Write)
Factory
Data range or item description
set value
18H
Set data lock function
R/W
0 to 7
19H
RUN/STOP function
R/W
0: RUN 1: STOP
*1 For the current transformer input 2 function, Z-168 specification is required.
*7
0
0
*2
For a unit without Z-168 specification, the read data is 0.
*3
When heating proportional band (P), integral time (I), derivative time (D) or anti-reset windup
(ARW) is set to 0, self-tuning (ST) cannot be set to 1, self-tuning start. Error code 2 is sent.
*4
The heat-side proportional band (P), integral time (I), derivative time (D) and anti-reset windup
(ARW) cannot be set while the self-tuning (ST) function is being executed. Error code 2 is
sent.
*5
Relay contact output: 20 sec
Voltage pulse output, trigger output for triac driving, triac output: 2 sec
*6
Relay contact output: 20 sec
Voltage pulse output, triac output: 2 sec
*7 Details of set data lock selection.
Set data
Set value (SV)
0
1
2
3
4
5
6
7
(-) Unsettable-Data locked
u
u
u
u
-
Alarm setting set value
(Alarm 1, Alarm 2)
u
u
u
u
(u) Settable-Data unlocked
Other setting items
u
u
u
u
-
The data lock function only prevents setting changes being made from the front keys.
changes can still be made through communication transmission.
Setting
Reading RO (read only) and R/W (read/write) unused data are not processed as an error at
read holding registers, but read data will be 0.
Any attempt to write unused data is not processed as an error.
the slave.
30
Data can not be written into
IMCB14-E1
7. DATA CONFIGURATION
„ Input Range Tables
Input Range Table 1
Input type
Input range
K
Thermocouple
(TC)
J
R
S
IMCB14-E1
0 to 200 qC
0 to 400 qC
0 to 600 qC
0 to 800 qC
0 to 1000 qC
0 to 1200 qC
0 to 1372 qC
0 to 100 qC
0 to 300 qC
0 to 450 qC
0 to 500 qC
0 to 800 qF
0 to 1600 qF
0 to 2502 qF
20 to 70 qF
0 to 200 qC
0 to 400 qC
0 to 600 qC
0 to 800 qC
0 to 1000 qC
0 to 1200 qC
0 to 450 qC
0 to 800 qF
0 to 1600 qF
0 to 2192 qF
0 to 400 qF
0 to 300 qF
0 to 1600 qC
0 to 1769 qC
0 to 1350 qC
0 to 3200 qF
0 to 3216 qF
0 to 1600 qC
0 to 1769 qC
0 to 3200 qF
0 to 3216 qF
Code
Input Range
K
01
K
02
K
03
K
04
K
05
K
06
K
07
K
13
K
14
K
17
K
20
K
A1
K
A2
K
A3
K
A9
J
01
J
02
J
03
J
04
J
05
J
06
J
10
J
A1
J
A2
J
A3
J
A6
J
A7
*1
R
01
*1
R
02
*1
R
04
*1
R
A1
*1
R
A2
*1
S
01
*1
S
02
*1
S
A1
*1
S
A2
Continued on the next page.
31
7. DATA CONFIGURATION
Continued from the previous page.
Input type
Input range
E
N
T
Thermocouple
(TC)
PL II
U
L
32
0 to 800 qC
0 to 1000 qC
0 to 1600 qF
0 to 1832 qF
0 to 1200 qC
0 to 1300 qC
0 to 2300 qF
0 to 2372 qF
-199.9 to +400.0 qC
-199.9 to +100.0 qC
-100.0 to +200.0 qC
0.0 to 350.0 qC
-199.9 to +752.0 qF
-100.0 to +200.0 qF
-100.0 to +400.0 qF
0.0 to 450.0 qF
0.0 to 752.0 qF
0 to 1300 qC
0 to 1390 qC
0 to 1200 qC
0 to 2400 qF
0 to 2534 qF
-199.9 to +600.0 qC
-199.9 to +100.0 qC
0.0 to 400.0 qC
-199.9 to +999.9 qF
-100.0 to +200.0 qF
0.0 to 999.9 qF
0 to 400 qC
0 to 800 qC
0 to 800 qF
0 to 1600 qF
Code
Input Range
*2
*2
*2
*2
*2
*2
E
E
E
E
N
N
N
N
T
T
T
T
T
T
T
T
T
A
A
A
A
A
U
01
02
A1
A2
01
02
A1
A2
01
02
03
04
A1
A2
A3
A4
A5
01
02
03
A1
A2
01
*2
U
02
U
03
*2
U
A1
*2
U
A2
U
A3
L
01
L
02
L
A1
L
A2
Continued on the next page.
IMCB14-E1
7. DATA CONFIGURTION
Continued from the previous page.
Input type
*1
*2
Input range
-199.9 to +649.0 qC
-199.9 to +200.0 qC
-100.0 to +50.0 qC
-100.0 to +100.0 qC
-100.0 to +200.0 qC
0.0 to 50.0 qC
0.0 to 100.0 qC
0.0 to 200.0 qC
0.0 to 300.0 qC
Pt100 :
0.0 to 500.0 qC
-199.9 to +999.9 qF
-199.9 to +400.0 qF
-199.9 to +200.0 qF
RTD
-100.0 to +100.0 qF
-100.0 to +300.0 qF
0.0 to 100.0 qF
0.0 to 200.0 qF
0.0 to 400.0 qF
0.0 to 500.0 qF
-199.9 to +649.0 qC
-199.9 to +200.0 qC
-100.0 to +50.0 qC
-100.0 to +100.0 qC
JPt100 :
-100.0 to +200.0 qC
0.0 to 50.0 qC
0.0 to 100.0 qC
0.0 to 200.0 qC
0.0 to 300.0 qC
0.0 to 500.0 qC
Accuracy is not guaranteed between 0 to 399 qC (0 to 799 qF).
Accuracy is not guaranteed between -199.9 to -100.0 qC (-199.9 to -158.0 qF).
IMCB14-E1
Code
Input Range
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
P
P
P
P
P
P
P
P
P
P
01
02
03
04
05
06
07
08
09
10
A1
A2
A3
A4
A5
A6
A7
A8
A9
01
02
03
04
05
06
07
08
09
10
33
7. DATA CONFIGURATION
Input Range Table 2
Input type
Input range
DC 0 to 5 V
DC 0 to 10 V*
DC 1 to 5 V
Current input
DC 0 to 20 mA
(mA)
DC 4 to 20 mA
* For this voltage range, Z-1010 specification is required.
Code
Input Range
Voltage input
(V)
34
0. 0 to 100.0 %
4
5
6
7
8
01
01
01
01
01
IMCB14-E1
8. TROUBLESHOOTING
!
WARNING
To prevent electric shock or instrument failure, always turn off the system
z
power before replacing the instrument.
To prevent electric shock or instrument failure, always turn off the power
z
before mounting or removing the instrument.
To prevent electric shock or instrument failure, do not turn on the power until
z
all the wiring is completed.
To prevent electric shock or instrument failure, do not touch the inside of the
z
instrument.
All wiring must be performed by authorized personnel with electrical
z
experience in this type of work.
This section lists some basic causes and solutions for Modbus communication problems.
If you can not find a solution, contact your nearest RKC sales office or agent for additional
information about replacement or repair.
Symptom
No response
Probable cause
The controller power is not turned on
Solution
Turn on the power
There communication cable is improperly Confirm the connection method
connected
Breakage in the communication cable
Replace the cable
Detachment of the communication cable
Confirm the connection condition
Problems with the connectors or contacts
Check and replace the wiring in the
connector
The communication speed or bit structure Confirm each setting
settings are different
The address specification is different
Confirm the address numbers
A transmission error (overrun error, framing Re-transmit after time-out occurs or
error, parity error or CRC-16 error) is found in verify communication program
the query message
The time interval between adjacent data in the
query message is too long, exceeding 24 bit's
time
Instrument failure
Replace instrument or return for
repair
Continued on the next page.
IMCB14-E1
35
8. TROUBLESHOOTING
Continued from the previous page.
Symptom
Probable cause
Solution
Error code 1
Function code error
(An unsupported function code was
specified)
Confirm the function code
Error code 2
Written to read only data.
Confirm the
register
address
of
holding
Any address other than 0000H to 0019H
is specified.
PID constants or anti-reset windup Set the PID constants and anti-reset
(ARW) data are set to 0 and 1 is entered windup (ARW) data to any number
at self-tuning (ST) function
other than 0.
Either one of PID constants and anti-reset Set the self-tuning (ST) function to 0.
windup (ARW) data are written during
execution of the self-tuning (ST) function.
Error code 3
The data written exceeds the setting Confirm the setting data
range.
When the specified number of data items Re-set the data within the range of 1
in the query message exceeds the to 125 (0000H to 007DH).
maximum number of data items available.
Error code 4
Self-diagnostic error
Turn off the power to the instrument.
If the same error occurs when the
power is turned back on, contact your
nearest RKC sales office or agent.
Error codes 1 to 4 indicate that an error response message has been transmitted.
36
IMCB14-E1
The 1st edition:
Sep. 1999
RKC INSTRUMENT INC.
HEADQUARTERS: 16-6, KUGAHARA 5-CHOME, OHTA-KU TOKYO 146-8515 JAPAN
PHONE: 03-3751-9799 (+81 3 3751 9799)
E-mail: info@rkcinst.co.jp
FAX:
03-3751-8585 (+81 3 3751 8585)
IMCB14-E1
SEP.1999