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MELSEC-Q
3 SPECIFICATIONS
3.3.2 Details of I/O signals
I/O signals for the A/D converter modules are explained in detail below.
(1) Input signals
Device No. Signal Name Description
X0 Module READY
(1) When the PLC CPU is powered on or reset, this signal turns on once the
preparation for A/D conversion has been completed, and A/D conversion
processing is then performed.
(2) When the Module READY signal is off, A/D conversion processing is not performed.
Module READY (X0) turns off in the following situations:
• During offset/gain setting mode
• When the A/D converter module has a watchdog timer error
1
X1
Temperature drift
compensation flag
(1) When A/D conversion processing is being performed with the temperature drift
compensation function on, the flag indicating temperature drift compensation status
(X1) turns ON.
X8
High resolution
mode status flag
(1) This turns ON when in high resolution mode.
X9
Operating
condition setting
completed flag
(1) This is used as an interlock condition for turning the operating condition setting
request (Y9) ON/OFF when the setting for A/D conversion enable/disable (buffer
memory address 0: Un\G0) is changed.
(2) When the operating condition setting completed flag (X9) is OFF, A/D conversion
processing is not performed. Under the following conditions, the operating condition
setting completed flag (X9) turns OFF.
• When Module READY (X0) is OFF
• When operating condition setting request (Y9) is ON
A
/D conversion
completed (XE)
Module READY (X0)
Operating condition
setting completed (X9)
Operating condition
change request (Y9)
Performed by the A/D converter module
Performed by the sequence program
1 A watchdog timer error occurs when the program calculations are not completed
within the scheduled time due to malfunctions of A/D converter module hardware.
When a watchdog timer error occurs, the RUN LED for the A/D converter module
turns off.