VIPA System 200V IM Series, Manual

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Chapter 8 Ethernet coupler
Manual VIPA System 200V
8-22 HB97E - IM - Rev. 06/29
With the following Modbus function codes a Modbus master can access a
Modbus slave. The description always takes place from the point of view of
the master:
Code Command Description
01h Read n Bits Read n Bits of master output area 0x
02h Read n Bits Read n Bits of master input area 1x
03h Read n Words Read n Words of master output area 4x
04h Read n Words Read n Words master input area 3x
05h Write one Bit Write 1 Bit to master output area 0x
06h Write one Word Write 1 Word to master output area 4x
0Fh Write n Bits Write n Bits to master area 0x
10h Write n Words Write n Words to master area 4x
17h Write n Words
and
Read m Words Write n words into master output area 4x
and the respond contains m read words of
the master input area 3x
The Ethernet coupler from VIPA does not differentiate between digital and
analog data!
Note!
The Byte sequence in a Word always is:
1 Word
High
Byte Low
Byte
If the slave announces an error, the function code is send back with a "OR"
and 80h. Without an error, the function code is sent back.
Coupler answer: Function code OR 80h
→
Error
Function code
→
OK
This function enables the reading from a slave bit by bit.
Command telegram
ModbusTCP-
Header Slave address Function code Address
1
st
Bit
Number of
Bits
x x 0 0 0 6
6Byte 1Byte 1Byte 1Word 1Word
Respond telegram
ModbusTCP-
Header Slave address Function code Number of
read Bytes
Data
1
st
Byte
Data
2
nd
Byte
...
x x 0 0 0
6Byte 1Byte 1Byte 1Byte 1Byte 1Byte
max. 252Byte
Overview
Respond of the
coupler
Read n Bits
01h, 02h
max. 255Byte