A little help on motion

Hi all

i asking for a little help or a few pointers to a program i am doing and i cant seem to get the sequence correct.

i am using Tia portal v15,1

i am moving a platform up & dwon according to the position requested, now because of the circumstances i am unable to use an encoder so i am using limit switches for the positions which are fixed accurately mechanically for the position required and there are 3 of them in total:

0 = Home

1 = middle

2 = High

the platform moves in a sequence:

0 to 1 (foward motion)

1 to 2 (foward motion)

2 to 1  (backward motion)

1 to 2 (foward motion)

2 to 1 (backward motion)

1 to 0 (backward motion)

these happen according to an external signal, so if signal for 1 is given then platform moves to 1 then gives a signal out to say its at position. but it will only ever give those signals in that order.

i am wanting to just use is the MC_MOVEJOG function which i have done but i cant get the logic correct because it never stops on the switch, the switch gives it the siganl to stop but just passes the switch by 50mm by the time it stops and this is creating a problem on the middle (1) switch.

any ideas on how i can achieve this?

thanks

Only allow limit switch 1 to reset your SR latch if the requested position is position 1.

 Please let me add:

-also increase Jerk (rate of change of deceleration/acceleration) if needed

jacek d

Increase deceleration value. If it can't help alone then also decrease velocity.