Functions; Read Coil Command (0X01) - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

Modbus Communication

3.5 Functions

3.5 Functions
Supported Command Set
The NXGpro Control implements the following Modbus™ commands:
● Read coil (function code 0x01)
● Read holding registers (function code 0x03)
● Write multiple coils (function code 0x0F)
● Write single register (function code 0x06)
● Loop back diagnostic test (function code 0x08)
● Write multiple registers (function code 0x10)
Commands are issued by the Modbus™ master (PLC) and sent over the network to the
Siemens slave[s]. Commands are listed and described in the sections that follow.
3.5.1

Read Coil Command (0x01)

Description
The "read coil" command allows you to obtain the ON or OFF status of logic coils used to
control discrete outputs from the addressed slave.
Coils are numbered beginning from 0 (coil number 1 = 0, coil number 2 = 1, and so on).
Example
A sample of a "read coil" request to read coils 0020 to 0056 from a slave device number 3
and the associated response is given below.
Read Coil Command
TX (Request)
RX (Response)
The meaning of the sample request and associated response is detailed in the following tables.
Request Details
Table 3-24 Read Coils Request (TX) to Master
Field Name
Slave Address
Function
Start address of coils to read (high)
Start address of coils to read (low)
64
Value (in Hex)
0x01
0x01
0x00
0x13
01 01 00 13 00 25 -- --
01 01 CD 6B B2 0E 1B -- --
Description
0x01 = 1 decimal
Read coils command
Start address is coil number 20
Function Manual, AB, A5E33486415A
NXGpro Communication