Modbus Rtu Command Message Frame; Response In Normal Status; Response In Abnormal Status; Error Code Contents - Panasonic FP0R User Manual

MODBUS RTU command message frame

START
3.5-character time
ADDRESS (Unit No.)
FUNCTION
DATA
CRC
END

Response in normal status

The same message as a command is returned for single write command.
A part of a command message (6 bytes from the beginning) is returned for multiple write command.

Response in abnormal status

In case a parameter disabled to be processed is found in a command (except transmission error)
Slave address (unit number)
Function code + 80H
Error code
CRC

Error code contents

1: Function code error
2: Device number error (out of range)
3: Device quantity error (out of range)
Reception done judgment time
The process for receiving a message completes when the time that is exceeding the time mentioned
below has passed after the final data was received.
Baud rate
2400
4800
9600
19200
38400
57600
115200
Note) The reception done judgment time is an approx. 32-bit time.
7-50
ADDRESS FUNCTION
8 bits 8 bits
8 bits, 0 to 99 (decimal)
Note1) 0= Broadcast address
Note2) Slave unit No. is 1 to 99 (decimal)
Note3) For MODBUS, 0 to 247 (decimal)
8 bits
Varies depending on commands.
16 bits
3.5-character time (Differs depending on baud rate. Refer to reception
judgement time.)
One of either 1, 2 or 3
Reception done judgment time
Approx. 13.3 ms
Approx. 6.7 ms
Approx. 3.3 ms
Approx. 1.7 ms
Approx. 0.8 ms
Approx. 0.6 ms
Approx. 0.3 ms
DATA CRC CHECK
n*8 bits 16 bits
END
3.5-character time