User Manual

DOUT16B-2 Digital Output Module User Manual Page 8 of 13
5 COMMUNICATION CONFIGURATION AND MODBUS COMMUNICATION PROTOCOL
5.1. RS485 COMMUNICATION PORT
DOUT16B-2 is an expansion output module with RS485 communication port, which follows
Modbus-RTU communication protocol.
Communication Parameters
Module Address 100 (range 100-115)
Baud Rate 9600bps
Data Bit 8-bit
Parity Bit None
Stop Bit 2-bit
5.2. INFORMATION FRAME FORMAT EXAMPLE
5.2.1. FUNCTION CODE 01H
Slave address is 64H (decimal 100), read 10H (decimal 16) status of starting address 64H (decimal
100).
Table 2 Function Code 01H Master Request Example
Request
Bytes
Example (Hex)
Slave address
1
64 Send to slave 100
Function code
1
01 Read status
Starting address
2
00 Starting address is 100
64
Count number
2
00 Read 16 status
10
CRC code
2
75 CRC code which calculated by master
EC
Table 3 Function Code 01H Slave Response Example
Response
Bytes
Example (Hex)
Slave address
1
64 Respond slave address 100
Function code
1
01 Read status
Read count
1
02 16 status (total 2 bytes)
Data 1
1
01 The content of address 07-00
Data 2
1
00 The content of address 0F-08
CRC code
2
F4 CRC code which calculated by slave.
64
The value of status 07-00 is indicated as 01H in Hex, and 00000001 in binary. Status 07 is the
high-order byte, 00 is the low-order byte. The state of status 07-00 is
OFF-OFF-OFF-OFF-OFF-OFF-OFF-ON.