315-4PN33

Without an error, the function code is sent back.
Slave answer: Function code OR 80h ® Error
Function code ® OK
1 word
High-byte Low-byte
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.
Code 01h: Read n bits of master output area 0x
Code 02h: Read n bits of master input area 1x
Command telegram
Slave address Function code Address 1. bit Number of bits Check sum CRC/
LRC
1byte 1byte 1word 1word 1word
Respond telegram
Slave
address
Function
code
Number of
read bytes
Data 1.
byte
Data 2.
byte
... Check sum
CRC/LRC
1byte 1byte 1byte 1byte 1byte 1word
max. 250byte
03h: Read n words of master output area 4x
Byte sequence in a
word
Check sum CRC, RTU,
LRC
Read n bits 01h, 02h
Read n words 03h, 04h
VIPA System 300S Deployment PtP communication
Modbus - Function codes
HB140 | CPU | 315-4PN33 | GB | 14-43 101