User`s manual

SH-300 User’s Manual Connection with PLC
Page 77 of 103
4.16 MODBUS RTU/ASCII and RTU/ASCII EXTEND protocol
1. Introducing Modbus Protocol
SH-300 communicates by using a master–slave technique, in which one SH-300(the master)
can send query message. one programmable controller(the slave) responds according to the
requested data supplied by SH-300. The Modbus protocol establishes the format for the master’s
query by placing into it the device address, a function code, any data to be sent, and
error–checking field. The slave’s response message is also constructed by using Modbus
protocol. It contains fields confirming the action taken, any data to be returned, and an
error–checking field. The returned data bytes contain the data collected by the slave, such as
register values or coil status. If error occurred in receipt of the message, or if the slave is unable
to perform the requested action, the slave will construct an error message and send it as its
response.
2. MODBUS RTU/ASCII and RTU/ASCII EXTEND communication parameter configuration:
Item content
SH-300 COM port 9 pin COM port
Default parameter (RTU) Consistent with PLC Port
Default parameter (ASCII) Consistent with PLC Port
Station No. 1-247,1 is windows default
Protocol MODBUS RTU/ASCII, RTU/ASCII EXTEND
Distance (Max.) 15m/100m (twisted-pair)
Communication mode RS232/485/422
Cable type MODBUS-RS232/485/422
Coil variable address type 0X
Discrete variable address type 1X
Register variable address type 3X/4X/5X/6X
3. Connection guidance of Special cable
MODBUS-RS232
SH-300 side 2RXD TXD slave device
9 pin D shape 3 TXD RXD side
Female plug 5GND GND
MODBUS-RS485
1 TD+
RD+
SH-300 side 9 RD+ TD+ Slave device
9 PIN D shape 6 TD-
RD-
side
Female plug
8 RD-
TD-
5 GND
GND
MODBUS-RS422
1 TD+
RD+
SH-300 side 9 RD+
TD+
slave device
9 pin D shape 6 TD-
RD-
side
Female plug 8 RD-
TD-
5GND
GND