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6.9 Troubleshooting ( General-purpose Serial
Communication)
Status indicator LEDs
Indication Function
Light (on): when reception error occurs
ERR Red Communication error
Off: when received data was retrieved
Light (on): when setting error occurs
S. ERR Red Setting error
Off: Normal
Note) The details can be checked by monitoring the MCU status using F161 (MRCV) instruction.
Troubleshooting
Trouble Contents to check How to confirm
Is a communciation block installed? Check if the communication
block is installed firmly.
Is the wiring correct? Check the wiring again.
Communication is not
possible.
(ERR LED lights)
Isn’t there any problem in
environments such as noise?
Check the shielding.
S. ERR lights - Is the operation mode setting
correct?
- Isn’t it used excessively ignoring the
usage restrictions?
Read out and check the status
using F161 (MRCV) instruction.
Isn’t the request to send given
redundantly during transmission?
In case of RS232C communication
block, isn’t transmission forbidden by
CTS signal?
Isn’t operation error occurring when
executing MTRN instruction?
Review the program.
Is the setting for the communication
conditions the same as the one for the
device communicated?
Transmission is not
possible.
Is the setting of the method for
detecting “reception done” the same
as the one for the device
communicated?
Check the setting reading the
status using F161 (MRCV)
instruction.
Isn’t reception error occurring?
Isn’t the reception buffer FULL error
occurring?
If the error occurs, the operation
cannot be restarted without performing
CH reset.
Is the operation mode general-
purpose communication?
(Has the operation mode been
changed using MTRN instruction?)
Check the setting reading the
status using F161 (MRCV)
instruction.
Reception is not possible.
When data is not received properly:
(Isn’t it multiplex reception? Isn’t there
garbage in the buffer cuased by noise
or something?)
Review the program.
Check the setting reading the
status using F161 (MRCV)
instruction.
ALARM lights Hardware error Please contact your dealer.