Troubleshooting When Using Built-In Analog Input - Mitsubishi Electric MELSEQ FX3S Series User Manual

FX Series Programmable Controllers
3S
User's Manual - Hardware Edition

11.3.10 Troubleshooting when using built-in analog input

This subsection describes troubleshooting methods and error statuses.
If the A/D conversion data is not input, or if the proper digital value is not input, check the following items:
• Wiring
• Special devices
• Programs
1. Wiring check
Check the following items for wiring:
• Use 2-core twisted shielded pair cable for the analog input line. In addition, be sure to separate the analog
input line from other power lines or inductive lines.
2. Special device check
Check whether the special devices for the PLC are being used correctly:
• Input data
Verify that the special device of the selected channel is correctly selected. This special device should be
selected depending on the channel.
• 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.
• Error status
Check that no error is detected in the PLC. If an error is detected, check the details of the error, and then
check the wiring and programs.
3. Program check
Check the following items for the program:
• Check of storage devices
Verify that different values are not being stored in the same device by other parts of the program.
4. Error status check
If an error occurs in the PLC, 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.
b6 to b15
To solve the problem, refer to the troubleshooting method described below:
1) Over-scale detection (b0, b1)
a) Description of error
The input analog value (voltage value) is outside the specified range.
The input voltage value is over the specified upper limit of 10.2 V.
b) Remedy
Check that the input analog value is within the specified range.
Also check the wiring.
106
→ For a detailed description of wiring, refer to Subsection 11.3.6.
→ For a detailed description of special devices, refer to Subsection 11.3.7.
Bit
b0 Channel-1 over-scale detection
b1 Channel-2 over-scale detection
b2 Unused
b3 Unused
b4 EEPROM error
b5 Averaging time setting error (common ch1 and ch2)
Unused
11.3 Built-in analog input function
Description
11 Use of Built-in Analog