4 Step Ladder Instructions Program Example 1: 1. Use of IST instruction M1000 S X10: Individual operation X11: Zero return X12: Step operation X13: One cycle operation X14: Continuous operation X15: Zero return enabled switch X16: Start switch X17: Stop switch 2. When IST instruction is being executed, the following special auxiliary relays will switch automatically. M1040: Operation forbidden M1041: Operation starts M1042: Pulse output enabled M1047: STL monitor enabled S0: Initiates manual operation S1: Initiates zero return S2: Initiates auto operation 3. S10 ~ S19 are for zero return and cannot be used as general steps.
When S0 ~ S9 are in use, S0 ~ S2 represent manual operation mode, zero return mode and auto operation mode. Therefore, in the program, you have to write the circuit of the three steps in advance. 4. When switched to S1 (zero return) mode, any On in S10 ~ S19 will result in no zero return. 5. When switched to S2 (auto operation) mode, any On of the S in D 1 ~ D 2 or M1043 = On will result in no auto operation. Program Example 2: 1. Robot arm control (by IST instruction): a) Motion request: Separate the big ball and small ball and move them to different boxes. Configure the control panel for the control. b) Motions of the robot arm:
descending, clipping ball, ascending, right shifting, releasing ball, ascending, left shifting. c) I/O devices: Left-limit X1 Right-limit X2 (big) Right-limit X3 (small) Upper-limit X4 Y2 Y3 Y0 Y1 Big Small Ball size sensor X0 Lower-limit X5 2. Operation modes: Manual operation: Turn On/Off of the load by a single button. Zero return: Press the zero return button to automatically zero-return the machine. Auto operation: a) Single step operation: Press “auto start” button for every one step forward. b) One cycle operation: Press “auto start” button at the zero point. After a cycle of auto operation, the operation will stops at the zero point.
Press “auto stop” button in the middle of the operation to stop the operation and press “auto start” to restart the operation. The operation will resume until it meets the zero point. c) Continuous operation: Press “auto start” button at the zero point to resume the operation. Press “auto stop” to DVP-PLC Application Manual 4-20 IST X10 S20 S60