Mitsubishi MELSEC iQ-F, User Manual

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4 FUNCTIONS
4.8 Disconnection Detection Function
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4
4.8
Disconnection Detection Function
This function detects disconnection of a thermocouple or resistance temperature detector.
Notification of disconnection
• Disconnection detection (1) is stored in a bit corresponding to the channel of 'Disconnection detection flag' (Un\G41).
• 'Disconnection detection signal' (Un\G69, b6) turns on.
• The ALM LED flashes.
• An alarm code is stored in 'Latest alarm code' (Un\G2). (

Page 103 List of Alarm Codes)
• A value specified in 'CH1 Conversion setting at disconnection detection' (Un\G534) (Value just before disconnection,
Upscale, Downscale, or Any value) is stored in 'CH1 Digital output value' (Un\G400).
• The value calculated with the scaling function and shift function is stored in 'CH1 digital operation value' (Un\G402) and
'CH1 digital output value' (Un\G400).
• The digital output value or digital operation value is stored in 'CH1 logging data' (Un\G10000 to 19999) depending on the
'CH1 logging data setting' (Un\G536).
• The 'CH1 maximum value' (Un\G404) and 'CH1 minimum value' (Un\G406) are updated with the maximum and minimum
values of the digital operation value.
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.
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 'Input signal error/Disconnection detection automatic clear enable/disable
setting' (Un\G304).
■
Case of Enable (0)
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' (Un\G69, b6)
automatically turns off and the ALM LED turns off. However, the alarm code stored in 'Latest alarm code' (Un\G2) is not
cleared. Turn off
→
on
→
off 'Error clear request' (Un\G70, b15) to clear the alarm code.
Connection status State of conversion enable/disable setting Disconnection detection flag
No disconnection
Conversion enable 0 (OFF)
Conversion disable
Disconnection
Conversion enable 1 (ON)
Conversion disable 0 (OFF)
No connection
Conversion enable 1 (ON)
Conversion disable 0 (OFF)
A
B
b
A
B
b
A
B
b