Mitsubishi Electric QD77MS User Manual page 812

[2] Precautions on parameter setting
(1) The external I/O signal logic switching parameters are validated when the
PLC READY signal [Y0] is turned OFF to ON. (The logic is negative right
after power-on.)
(2) If the logic of each signal is set erroneously, the operation may not be carried
out correctly.
Before setting, check the specifications of the equipment to be used.
(3) When the same external input signal is set to use to the multiple axes in
"[Pr.80] External input signal selection" or "[Pr.95] External command signal
selection" in the QD77MS16, "Input signal logic selection" of those axes
should be the same. Otherwise, the error "Input signal logic selection setting
error" (error code: 938) occurs when the PLC READY signal [Y0] is turned
ON, and the READY signal [X0] will not be turned ON.
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Chapter 14 Common Functions