10 (48)
3.2
Supported Modbus Commands
#
Name
Description
3
Read multiple registers
All mapped to the same register space.
4
Read input registers
6
Write single register
16
Write multiple registers
23
Read/Write registers
70
Anybus command
Custom Modbus command, see below
3.2.1
Error Handling
•
Modbus reads, addressing undefined registers, return zeroes.
•
Modbus writes, addressing undefined registers, do not return any error.
•
Modbus writes containing invalid data to registers do not return any error.
•
Modbus writes, addressing read-only registers, do not return any error.
3.2.2
Endianess
•
If 8-bit data types are mapped to Modbus registers, the first byte is mapped to LSB and the
second byte is mapped to MSB of the Modbus register.
3.2.3
Anybus Command (Modbus Function Code 70)
This command can be used to send an Anybus CompactCom message. Allowed content depends
on which network is connected to the Anybus CompactCom. The data field part of the telegram
is composed by concatenating the content for each configuration option to include. Note that
the total amount of configuration options to set is limited to 244 bytes of data. Please refer to
the applicable network appendix for more information.
The content of the telegram will be stored and used at the next startup. It is not necessary to
send this telegram at each startup. Instead it is recommended to send it once to customize the
Anybus CompactCom behavior.
Request format:
0
1
2
3
4
5
6
7
8
9
10–n
(n+1)-
(n+2)
Address
Function
Size
Data Field
CRC
(Address)
70
66
1
1
0
1 7
0
Size of
Data
Field
0
0-244 bytes of
data,
configuring the
Anybus
CompactCom
behavior
(CRC)
The content of the data field depends on which network is connected. Please refer to the applicable
network appendix for details.
Response format
0
1
2
3
4
5
6
7
8
9
10–11
Address
Function
Size
CRC
(Address)
70
2
1
1
0
17
0
0
0
(CRC)
Anybus
®
CompactCom
™
B40 Modbus Serial User Manual
SCM-1202-130 1.1 en-US