Chapter 6 Applied Instructions 2. When M0 is OFF, the execution of the program goes from NETWORK 1 to NETWORK 2 to NETWORK 3 in sequence, and the CJ instruction is not executed. Example 2 1. You can use the CJ instruction between the MC and the MCR instructions in the five conditions below. (a) The execution of the program jumps from the part of the program outside one MC/MCR loop to the part of the program outside another MC/MCR loop. 6_ (b) The execution of the program jumps from the part of the program outside the MC/MCR loop to the part of the program inside the MC/MCR loop.
(c) The execution of the program jumps from the part of the program inside the MC/MCR loop to the part of the program inside the MC/MCR loop. (d) The execution of the program jumps from the part of the program inside the MC/MCR loop to the part of the program outside the MC/MCR loop. (e) The execution of the program jumps from the part of the program inside one the MC/MCR loop to the part of the program inside another the MC/MCR loop. 2. When the PLC executes an MC instruction, it puts the previous state of the switch contact onto the top of the stack inside the PLC. The stack is controlled by the PLC, and cannot be changed.
When the PLC executes the MCR instruction, the PLC pops the previous state of the switch contact from the top of the stack. Under the conditions listed in (b), (d), and (e) above, the number of times the items are pushed onto the stack may be different from the number of times the items are popped from the stack. When this situation occurs, at most 32 items can be pushed 6-151