User`s manual

39
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
6 Related Devices and Communication Status
6.3 Special Auxiliary Relays
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
M: Master S: Slave R: Read W: Write
M8408 M8428 Retry M
Set while the master sends retries when the slave
fails to respond in time.
Special clear conditions:
1) Power on
2) STOP to RUN
3) If another MODBUS command is triggered
As long as the slave responds on one of the retries
the error flag will not be set.
R
M8409 M8429 Timeout S
Set if a response timeout occurs.
Special clear conditions:
1) Power on
2) STOP to RUN
3) If another MODBUS command is triggered
Note: If the number of retries is > 0, the error flag is
not set until the selected number of retries
failed by a timeout (or another failure).
R
Special Device
Name Valid Detailed Description R / W
CH1 CH2