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MELSEC-Q
 
3   SPECIFICATIONS AND FUNCTIONS 
 
3.3 Specifications of input/output signals with PLC CPU 
3.3.1 List of input/output signals with PLC CPU 
The QD75 uses 32 input points and 32 output points for exchanging data with the PLC 
CPU. 
The input/output signals when the QD75 is mounted in slot No. 0 of the main base unit 
are shown below. 
Device X refers to the signals input from the QD75 to the PLC CPU, and device Y 
refers to the signals output from the PLC CPU to the QD75. 
 
Signal direction: QD75   PLC CPU  Signal direction: PLC CPU   QD75 
Device No.  Signal name  Device No.  Signal name 
X0  QD75 READY  Y0  PLC READY 
X1  Synchronization flag  Y1  All axis servo ON 
X2 Y2 
X3 
Use prohibited 
Y3 
Use prohibited 
X4 Axis 1  Y4 Axis 1 
X5 Axis 2  Y5 Axis 2 
X6 Axis 3  Y6 Axis 3 
X7 Axis 4 
M code ON 
Y7 Axis 4 
Axis stop 
X8  Axis 1  Y8  Axis 1  Forward run JOG start 
X9  Axis 2  Y9  Axis 1  Reverse run JOG start 
XA  Axis 3  YA  Axis 2  Forward run JOG start 
XB Axis 4 
Error detection 
YB  Axis 2  Reverse run JOG start 
XC  Axis 1  YC  Axis 3  Forward run JOG start 
XD  Axis 2  YD  Axis 3  Reverse run JOG start 
XE  Axis 3  YE  Axis 4  Forward run JOG start 
XF Axis 4 
BUSY 
YF  Axis 4  Reverse run JOG start 
X10 Axis 1  Y10 Axis 1 
X11 Axis 2  Y11 Axis 2 
X12 Axis 3  Y12 Axis 3 
X13 Axis 4 
Start complete 
Y13 Axis 4 
Positioning start 
X14 Axis 1  Y14 Axis 1 
X15 Axis 2  Y15 Axis 2 
X16 Axis 3  Y16 Axis 3 
X17 Axis 4 
Positioning complete 
Y17 Axis 4 
Execution prohibition flag 
X18 Y18 
X19 Y19 
X1A Y1A 
X1B Y1B 
X1C Y1C 
X1D Y1D 
X1E Y1E 
X1F 
Use prohibited 
Y1F 
Use prohibited 
 
Important 
 
[Y2 to Y3], [Y18 to Y1F], [X2, X3], and [X18 to X1F] are used by the system, and cannot be 
used by the user. 
If these devices are used, the operation of the QD75 will not be guaranteed.