IDEC KW2D Series User Manual page 44

1 ModbusTCP Communication (Server)
■ Data fields
Function code
The number indicating the function.
Function code
01(01h)
02(02h)
03(03h)
04(04h)
05(05h)
06(06h)
15(0Fh)
16(10h)
In the case of an NG response, the value obtained by adding 80h to the function code is stored.
Contents
This is the data required for the processing specified by the function code.
Communication format of Data fields
●
Read the value of the coil relay or input relay
The host device (ModbusTCP client) reads the value of the coil relay or input relay of the KW2D Smart RFID Reader
(ModbusTCP Server). The number of continuous read bits is 1 to 32 bits. The function code is "01h" for the coil relay
and "02h" for the input relay. In case of error, the function code is "81h" (01h + 80h) for the coil relay and "82h" (02h
+ 80h) for the input relay.
Example: Read 32-bit (4 bytes) of data from input relay 0001.
Request
Function code Start address number
02h
（1 byte）
Input relays 0001 to 0016 are "1234h" and input relays 0017 to 0032 are "5678h"
ACK Reply
Function code
02h
（1 byte）
Example: Try to access an input relay with a slave address outside the range
NAK Reply
Function code
82h
（1 byte）
For details on the error code, refer to "Error code" on page 4-5.
4-2
01: Read the value of coil relay (000001 to 000016)
02: Read the value of input relay (100001 to 100032)
03: Read the value of holding register (400001 to 400032)
04: Read the value of input register (300001 to 300032)
05: Write a value to a coil relay (000001 to 000016)
06: Write a value to a holding register (400001 to 400032)
15: Write values to multiple coil relays (000001 to 000016)
16: Write values to multiple holding registers (400001 to 400032)
Number of bits
of data to read
00h 00h 00h
（2 bytes） （2 bytes）
Number
Read value
of data
04h 34h 12h
（1 byte） （1st byte） （2nd byte） （3rd byte） （4th byte）
Error code
02h
（1 byte）
KW2D Series Smart RFID Reader User's Manual
Description
20h
78h 56h