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Entry type: FAQ Entry ID: 109478538, Entry date: 08/31/2015

How do you program the automatic stop at the limit switches in jogging mode with S7-1500 Motion Control?

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For this application you use the S7-1500 Motion Control instructions "MC_MoveAbsolute" and "MC_Halt".

With the SIMODRIVE drives you can use "Continuous positioning - positive" and "Continuous positioning - negative" in jogging mode to travel so that the axis makes a controlled stop automatically at the limit switches without generating errors, even when the jog command is still active.

You cannot use the "MC_MoveJog" instruction of the S7-1500 in this application case. With the S7-1500 SMC (SIMATIC Motion Control), in jogging mode the axis always travels position-controlled. In other words the axis does not usually travel beyond the software limit switch, but is positioned exactly at the limit switch position. In this case the error has to be acknowledged.

If you want to implement the functions as with SIMODRIVE, you program a jogging mode with the instructions "MC_MoveAbsolute" and "MC_Halt".

  • For the "MC_MoveAbsolute" instruction you specify a position of 1 to 3 mm before the position of the limit switch and a jogging speed.
  • With a positive edge of the jog button you trigger "MC_MoveAbsolute" instruction.
  • With a negative of the jog button you trigger the "MC_Halt" instruction.

In this way by pressing the jog button you start positioning to a position just before the limit switch. When you release the jog button, positioning is stopped and the axis stops. In this way you can jog the axis.
When the axis reaches the end position (1 to 3 mm before the limit switch), it stops automatically even if you continue to press the jog button.

In the example below the limit switches are at 0 and 2000mm. The jogging speed is preset at 50mm/s.

Fig. 01

Creation Environment
The screens in this FAQ response were created with STEP 7 (TIA Portal) V13 SP1.