Advantech ADAM-6000 series, User Manual

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And the response should be:
Figure 6-2 Response Comment Structure
6-3-2 Modbus Function Code Introductions
To full-fill the programming requirement, there is a series of function code standard for user’s
reference…
Code (Hex) Name Usage
01 Read Coil Status Read Discrete Output Bit
02 Read Input Status Read Discrete Input Bit
03 Read Holding Registers
04 Read Input Registers
Read 16-bit register. Used to read integer
or floating point process data.
05 Force Single Coil Write data to force coil ON/OFF
06 Preset Single Register Write data in 16-bit integer format
08 Loopback Diagnosis Diagnostic testing of the communication port
15 Force Multiple Coils Write multiple data to force coil ON/OFF
16 Preset Multiple Registers Write multiple data in 16-bit integer format
Table 6-1 Response Comment Structure
Function Code 01
The function code 01 is used to read the discrete output’s ON/OFF status of ADAM-6000 modules in a
binary data format.
Request message format for function code 01:
Command Body
Station
Address Function
Code Start Address
High Byte Start Address
Low Byte Requested Number
of Coil High Byte Requested Number
of Coil Low Byte
Example: Read coil number 1 to 8 (address number 00017 to 00024) from ADAM-6000 Modules
01 01 00 17 00 08