YASKAWA CP 040 RS422/485 Manual page 84

Serial communication protocols
Deployment - Modbus > Modbus - Function codes
Respond of the slave
Byte sequence in a word
Check sum CRC, RTU,
LRC
Slave address
Read n bits 01h, 02h
Command telegram
Slave address
1byte
Respond telegram
Slave address Function code
1byte 1byte
Read n words 03h, 04h
Command telegram
Slave address
1byte
84
If the slave announces an error, the function code is send back with an "OR" 80h.
Without an error, the function code is sent back.
Slave answer:
The shown check sums CRC at RTU and LRC at ASCII mode are automatically added to
every telegram. They are not shown in the data block.
The Slave address must be the same address as the parameterized Slave address
(OPTION4).
Code 01h: Read n bits of master output area 0x
Code 02h: Read n bits of master input area 1x
Function code
1byte
Number of
read bytes
1byte
03h: Read n words of master output area 4x
04h: Read n words master input area 3x
Function code
1byte
Function code OR 80h
Function code
1 word
High byte Low byte
Address 1. bit Number of bits
1word
Data 1. byte Data 2. byte
1byte 1byte
max. 250byte
Address 1. bit Number of words
1word
VIPA System SLIO
® Error
® OK
Check sum
CRC/LRC
1word
...
Check sum
CRC/LRC
1word
HB300 | CP | 040-1CA00 | en | 18-28
1word
Check sum
CRC/LRC
1word
1word