User`s manual

37
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
6 Related Devices and Communication Status
6.2 Communication setting for MODBUS
1
Outline
2
Specifications
3
System Configuration
4
Wiring
5
Communication Setup
6
Related Devices and Comm. Status
7
MODBUS Standard Commands
8
Master Specification
9
Slave Specification
10
Creating Programs
6.2 Communication setting for MODBUS
The following devices are used in the communication setting.
When using the communication port (Ch1), set D8400.
When using the communication port (Ch2), set D8420.
1) D8400 and D8420 (communication format)
By setting values to D8400 or D8420, the data length, parity, baud rate, etc. can be set.
The table below shows the contents of D8400 and D8420.
Bit No. Name
Contents
0 (bit = OFF) 1 (bit = ON)
b0 Data length 7-bit 8-bit
b1
b2
Parity
Parity
b2, b1
(0, 0): Not provided
(0, 1): Odd
(1, 1): Even
b3 Stop bit 1-bit 2-bit
b4
b5
b6
b7
Baud rate (bps)
b7, b6, b5, b4
(0, 0, 1, 1): 300
(0, 1, 0, 0): 600
(0, 1, 0, 1): 1200
(0, 1, 1, 0): 2400
b7, b6, b5, b4
(0, 1, 1, 1): 4800
(1, 0, 0, 0): 9600
(1, 0, 0, 1): 19200
b8 -11 Reserved
b12 H/W type RS232C RS485
b13-15 Reserved