H-38
6 Troubleshooting
6.4 Program Check
FX
3S
/FX
3G
/FX
3GC
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
FX
3U
-3A-ADP (2-channel Analog Input, 1-channel Analog Output)
4. Output setting data
Check that the special device of the selected channel is correctly selected. This special device should be
selected depending on the connected position and the channel.
5. Averaging time
Check that the set averaging time is within the specified range. The averaging time should be set in the range
from 1 to 4095. If the set averaging time is outside the specified range, an error occurs.
6. Setting whether or not each channel is used
Check whether each channel is set correctly.
Set a channel to OFF when using it. Set a channel to ON when not using it.
7. Error status
Check that no error is detected in the 3A-ADP.
If an error is detected, check the details of the error, and then check the wiring and programs.
→ For a detailed description of special devices, refer to Chapter 4.
6.4 Program Check
Check the following items for the program:
1. Clearing of error status at power on
When the power is turned off and then on again, the error status should be cleared (b6 and b7 should turn off)
using the program.
2. Check of storage devices
Verify that different values are not being stored in the same device by other parts of the program.
3. Device for setting specified digital value
Check that different values are not written to this device using other programs.
6.5 Error Status Check
If an error occurs in the 3A-ADP, the corresponding bit will turn ON.
The bit which is turned ON due to the error status is held ON until overwritten to OFF by the program or the
power is cycled. If b6 or b7 is turned ON, then it is necessary to clear the error status using the program the
next time the power of the PLC is cycled.
*1. A 3A-ADP hardware error (b6) is valid only when use of analog input is set.
Detection of power supply error is valid only when use of the analog input channel 2 is set.
*2. A 3A-ADP communication data error (b7) is valid only when use of analog input is set.
*3. Applicable for FX
3U/FX3UC Series PLC Ver. 2.70 or later and FX3S Series PLC.
The under-scale detection function is valid only for current input mode.
The FX
3G/FX3GC Series PLC are not supported.
Bit Description Bit Description
b0 Channel-1 over-scale detection b6
3A-ADP hardware error
(Power supply error included)
*1
b1 Channel-2 over-scale detection b7
3A-ADP communication data error
*2
b2 Output data setting error b8
Channel-1 under-scale detection
*3
b3 Unused b9
Channel-2 under-scale detection
*3
b4 EEPROM error b10 to b15 Unused
b5 Averaging time setting error - -
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