Communicating with the PLC
7.2 MODBUS communication
SINAMICS V20 Converter
Operating Instructions, 10/2019, A5E34559884-012
181
FC16 - Write Multiple Registers
When a message with FC = 0x10 is received, then 5 + N bytes of data are expected, that is,
FC16 has 5 + N bytes of data:
●
2 bytes for the starting address of register
●
2 bytes for the number of registers
●
1 byte for the byte count
●
N bytes for the register values
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
...
Byte N - 1 Byte N Byte N + 1 Byte N + 2
Address FC
(0x10)
Start address
Number of regis-
ters
Number
of bytes
...
Register N value CRC
High
Low
High
Low
High
Low
High
Low
Converter response
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Byte 8
Address
FC (0x10)
Start address
Number of registers
CRC
High
Low
High
Low
High
Low
Acyclic communication via MODBUS
Acyclic communication or general parameter access is realized using the Modbus registers
40601 … 40722.
Acyclic communication is controlled using 40601. 40602 contains the function code (always
= 47 = 2F hex) and the number of the following user data. User data are contained in
registers 40603 … 40722.
Overview of acyclic communication
Value in the register
Explanation
40601
40602
40603 … 40722
0
47
…
…
Write values for acyclic access
1
47
Request length [bytes]
Request data
Activate acyclic access
2
47
Response length [bytes]
Response data Response for a successful request
2
47
0
Error code
Response for an erroneous request
Error codes
1 hex: Invalid Length (invalid length)
2 hex: Invalid State (in the actual converter state, this action is not permitted)
3 hex:
Invalid function code (FC ≠ 2F hex)
4 hex: Response not ready (the response has still not been issued)
5 hex: Internal Error (general system error)
Incorrect access operations to parameters via data set 47 are logged in registers
40603 … 40722.
Summary of Contents for SINAMICS V20 Inverter
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