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ESERA-Automation, E-Service GmbH 2019
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Programming Manual Controller-Gateway-Station V1.0 R1.1
Page 13 of 77
5.3.
Modbus and ASCII data output
Modbus data of the 1-Wire gateway and the ESERA Station-200 can be queried in a 1-second cycle and can be
read or written. A maximum of 20 data points can be read with one Modbus query.
The 1-Wire Gateway and the ESERA Station-200 are equipped with automatic protocol recognition. After
commissioning, the 1-Wire Gateway or the ESERA Station-200 is in Modbus mode, therefore no data is output
via ASCII protocol. The continuous data output in ASCII mode only takes place after receipt of an ASCII
command or query. As soon as you send a Modbus query, the 1-Wire gateway or the ESERA Station switches
back to Modbus mode and no longer sends ASCII data on its own.
5.4.
Modbus function codes
Structure and function codes
Modbus RTU, RS485 interface
Structure and function codes
Modbus TCP, Ethernet interface
FC1,2 (reads single bits):
Example:
FC1,2 (reads single bits):
Example:
Controller No.
1
Transactionsno high
0
Function code
1
Transactionsno low
0
Startaddress high (Bit)
0
Protocol-Ident high
0
Startaddress low (Bit)
32
Protocol-Ident low
0
Number of bits high
0
Bytes from here
6
Number of bits low
8
Recognition
e.g. 1
CRC high
x
Functional code
1
CRC low
x
Startaddress high (Bit)
0
Startaddress low (Bit)
32
Number of bits high
0
Number of bits low
8
FC3,4 (reads words):
FC3,4 (reads words):
Controller No.
1
Transactionsno high
0
Function code
4
Transactionsno low
0
Startaddress high (Wort)
238
Protocol-Ident high
0
Startaddress low (Wort)
102
Protocol-Ident low
0
Number of words high
0
Bytes from here
6
Number of words low
9
Recognition
e.g. 1
CRC high
x
Function code
4
CRC low
x
Startaddress high (Wort)
238
Startaddress low (Wort)
102
Number of words high
0
Number of words low
9
FC5 (sets a Bit):
FC5 (sets a Bit):
Controller No.
1
Transactionsno high
0
Function code
5
Transactionsno low
0
Startaddress high (Bit)
0
Protocol-Ident high
0
Startaddress low (Bit)
32
Protocol-Ident low
0
Bit value high
255 or 0
Bytes from here
6
Bit value low
0
Recognition
e.g. 1
CRC high
x
Function code
5
CRC low
x
Startaderess high (Bit)
0
Startaderess low (Bit)
32
Bit value high
255 or 0
Bit value low
0
FC6 (writes one word):
FC6 (writes one word):