6. TROUBLESHOOTING MELSEC-A
6-3
6.2 When Wire Breakage Detection Flag is On
Cause Corrective action
Connection between thermocouple and
compensating conductor is incomplete.
Securely connect the thermocouple and compensating
conductor.
Terminal screw is loose. Tighten the terminal screws within the specified torque range.
The connected thermocouple or compensating
conductor has wire breakage.
Check the continuity of thermocouple and compensating
conductor, and replace the broken thermocouple or
compensating conductor.
The channel to which thermocouple is not
connected is designated as conversion enabled.
Confirm the channels for which the conversion enable is
designated and channel to which thermocouple is connected,
then correct the conversion enable designation.
6.3 When E
2
PROM Error Flag is On
Cause Corrective action
Error in the internal memory storing the offset
value/gain value set by user
Restart power for AJ65BT-68TD. *1
If the E
2
PROM error flag is still on after power restart, contact
the nearest representative or branch regarding the problem, as
hardware may be faulty.
*1 Restart power : Turn on the power supply again, or turn on the reset switch.
6.4 When Detected Temperature Value cannot be Read
Cause Corrective action
The channel used is designated as conversion
disabled.
Designate the channel as conversion enable in sequence
program.
Programmable controller CPU or master module
error
Confirm the programmable controller CPU and master module.
6.5 When Detected Temperature Value is Abnormal
Cause Corrective action
The thermocouple connected is different from
what is designated.
Designate the thermocouple connected.
Affected by noise.
Confirm the influence from grounding and adjacent devices,
then take measures against noise.
The Pt100 temperature-measuring resistor that
performs cold contact compensation, is either
broken off or disconnected from the terminal
block.
Confirm the connection and continuity of the Pt100
temperature-measuring resistor on the terminal block, and
connect or replace the Pt100 temperature-measuring resistor.
When performing cold contact compensation
externally, the cold contact compensation by
Pt100 temperature-measuring resistor is
enabled.
At the initial data setting, set the Pt100 cold contact
compensation disable flag (RY(n+5)7) to on.
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