Disconnection Detection Function - Mitsubishi Electric MELSEC iQ-R Series User Manual

1.7

Disconnection Detection Function

This function detects disconnection of a thermocouple, compensation lead wire, or resistance temperature detector.
Notification of disconnection
• Disconnection detection (1) is stored in a bit position corresponding to the channel number of 'Disconnection detection flag'
(Un\G41).
• 'Disconnection detection signal' (XC) turns on.
• The ALM LED flashes.
• An alarm code is stored in 'Latest alarm code' (Un\G2). ( Page 87 List of Alarm Codes)
• A value specified in 'CH1 Conversion setting at disconnection detection' (Un\G531) (Value just before disconnection,
Upscale, Downscale, or Any value) is stored in 'CH1 Measured temperature value' (Un\G400).
Relationship of disconnection detection and conversion enable/disable setting
The disconnection detection is executed only for a channel where conversion is set to be enabled. The following table shows
the relationship of disconnection detection and state of conversion enable/disable setting.
Connection status
No disconnection
Disconnection
No connection
Recovery from disconnection
When the cause of the disconnection is eliminated and the connection of external devices is established, the operation after
this recovery varies depending on the setting of 'Disconnection detection automatic clear enable/disable setting' (Un\G303).
■Enable (0) is set
Normal (0) is stored in the bit corresponding to 'Disconnection detection flag' (Un\G41) of the recovered channel. After Normal
(0) is stored in all the bits of 'Disconnection detection flag' (Un\G41), 'Disconnection detection signal' (XC) automatically turns
off and the ALM LED turns off. However, the alarm code stored in 'Latest alarm code' (Un\G2) is not cleared. Turn on and off
'Error clear request' (YF) to clear the alarm code.
■Disable (1) is set
'Disconnection detection flag' (Un\G41), 'Disconnection detection signal' (XC), and the ALM LED hold the status at the time of
the disconnection detection. To return to the normal status, make a recovery from disconnection of all the channels, and turn
on and off 'Error clear request' (YF).
1 FUNCTIONS
34
1.7 Disconnection Detection Function
State of conversion enable/disable setting
Conversion enable
A
Conversion disable
B
b
Conversion enable
A
Conversion disable
B
b
Conversion enable
A
Conversion disable
B
b
Disconnection detection flag
OFF
ON
OFF
ON
OFF