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SPECIFICATIONS
3.2 Function List
3.2.5 Cold junction temperature compensation resistor disconnection detection function
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1
OVERVIEW
2
SYSTEM
CONFIGURATION
3
SPECIFICATIONS
4
SETUP AND
PROCEDURES BEFORE
OPERATION
5
UTILITY PACKAGE (GX
CONFIGURATOR-TI)
6
PROGRAMMING
7
ONLINE MODULE
CHANGE
8
TROUBLESHOOTING
3.2.5 Cold junction temperature compensation resistor disconnection
detection function
This function detects disconnection of cold junction compensation resistor (RTD).
When a cold junction compensation resistor (RTD) connected with a relay terminal block is
disconnected, an error (error code 800) occurs. Consequently, the Error flag (XF) turns on
and the “ERR” LED blinks to notify the error.
(1) Condition for detecting disconnection of cold junction compensation
resistor (RTD)
Disconnection of the cold junction temperature compensation can be detected only
when the switch setting 4 of the intelligent function modules is set to “with cold
junction compensation”.
The following shows the conditions in which the disconnection of the cold junction
temperature compensation resistor (RTD) can be detected.
(2) Operation for detecting disconnection of cold junction compensation
resistor (RTD)
When disconnection of cold junction temperature compensation resistor (RTD) is
detected, conversion for every conversion-enabled channel stops.
The measured temperature value for cold junction temperature compensation resistor
(RTD) disconnection remains the same as the measured value prior to the
disconnection detection.
(3) Operation and processing for restoring disconnection of cold junction
compensation resistor (RTD)
Conversion processing does not restart even after the disconnection of the cold
junction temperature compensation resistor (RTD) is restored.
To restart the conversion processing, turn off the Error clear request (YF).
Table 3.7 Disconnection detection of cold junction temperature compensation resistor
Connection state
Cold junction temperature
with/without setting
Error flag
with
OFF
without
with ON
without OFF
with ON
without OFF
GND
RTD
Without disconnection
+
-
GND
RTD
With disconnection
+
-
GND
Without connection
+
-