Panasonic FPS Series User Manual page 262

FPΣ User's Manual
Modbus RTU slave function
After having received a command message from the master station, the slave stations send
back the response message based on the instructions received. Do not execute the
F145_WRITE and F146_READ instructions on slave stations.
Master
1
Modbus RTU command message frame
START
Transmission time for
3.5 characters
ADDRESS
(station no.)
FUNCTION
DATA
CRC
END
1)
FPWIN Pro does not support the address range from 0–247 of the Modbus RTU protocol.
Response in normal status
The same message as a command is returned for a single write command. A part of a
command message (6 bytes from the beginning) is returned for a multiple write command.
Response in abnormal status
If a parameter which is to be processed but is disabled is found in a command (except for a
transmission error):
ADDRESS FUNCTION + 80H
ERROR CODE
Slave
2
ADDRESS FUNCTION
8 bits 8 bits
8 bits, 0–99 (decimal)
0 = broadcast address
8 bits
Varies depending on the commands.
16 bits
Transmission time for 3.5 characters (differs depending on baud rate). Please refer to
"Reception done judgment time".
ERROR CODE
1: Illegal function
2: Illegal data address (no word address)
3: Illegal data value (not a multiple of 16)
8.8 Modbus RTU Communication
DATA CRC CHECK
n × 8 bits 16 bits
1)
CRC
END
Transmission time for
3.5 characters
245