User Manual

2-12
IM 04L21B01-17EN
2.6 Using Modbus to Read Data From and Write
Data to Other Devices
The FX is used as a Modbus master.
For the Modbus specifications, see section 6.3.
Setting the Serial Communication
Select Modbus-M as a protocol on the Basic settings. For detail, see section 2.4, “Setting
the Serial Communication.”
Setting the Modbus Master
◊ Press MENU (to switch to setting mode), hold down FUNC for 3 s (to switch to basic
setting mode), and select the Menu tab > Communication (Serial) > Modbus
master > Basic settings or Command settings.
Basic settings Command settings
Basic settings
• Read cycle
Set the data read cycle to 1s, 2s, 5s, or 10s.
• Timeout
Set the timeout value to 125 ms, 250 ms, 500 ms, 1 s, 2 s, 5 s, 10 s, or 1 min. The
timeout value is the maximum amount of time the FX waits for a response from the
specified slave after the FX sends a command.
• Retrials
Set the number of retrials when there is no response from the slave. Select Off, 1, 2, 3,
4, 5, 10, or 20.
• Inter-block delay
Set the amount of time the FX waits after receiving a response to send the next
command. Set the amount of time to Off, 5 ms, 10 ms, 15 ms, 45 ms, or 100 ms.
• Auto recovery
Set the auto recovery time from communication halt. Select Off, 1min, 2min, 5min,
10min, 20min, 30min, or 1h.
Command settings
• Master command number
Select 1-8 or 9-16 for the command numbers to be configured.
• Command type
Set the operation of transmitted commands to Off, R-M, W, or W-M.
R-M: Read to the communication input data (32-bit floating point type) from the slave.
W: Write the measurement channel (16-bit signed integer type) to the slave.
W-M: Write the computation channel (32-bit signed integer type) to the slave.
You can only select R-M and W-M on models that have the /M1, /PM1, or /PWR1 math
option.