Maintenance
and Troubleshooting
9–12
Maintenance and Troubleshooting
There are several instructions that can be used to help you debug your program
during machine startup operations.
S END
S PAUSE
S STOP
END Instruction: If you need a way to quickly disable part of the program, just insert
an END statement prior to the portion that should be disabled. When the CPU
encounters the END statement, it assumes that is the end of the program. The
following diagram shows an example.
New END disables X10 and Y1
Y0X0
END
X2
X3X1
X4
Y1
X10
Normal Program
Y0X0
END
X2
X3X1
X4
Y1
X10
END
PAUSE Instruction: This instruction provides a quick way to allow the inputs (or
other logic) to operate while disabling selected outputs. The output image register is
still updated, but the output circuits are not. For example, you could make this
conditional by adding an input contact or CR to control the instruction with a switch or
a programming device. Or, you could just add the instruction without any conditions
so the selected outputs would be disabled at all times.
PAUSE disables Y0 and Y1
Y0X0
END
X2
X3X1
X4
Y1
X10
Normal Program
Y0X0
END
X2
X3X1
X4
Y1
X10
PAUSE
Y0 – Y1
STOP Instruction: Sometimes during machine startup you need a way to quickly
turn off all the outputs and return to Program Mode. You can use the STOP
instruction. When this instruction is executed the CPU automatically exits Run Mode
and enters Program Mode. Remember, all outputs are turned off during Program
Mode. The following diagram shows an example of a condition that returns the CPU
to Program Mode.
Special
Instructions
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