Software.... Step7 Basic V15.0.0.1
PLC......... CPU1214, FW4.2
Technology.. Motion Control V6
              - MC_HOME, Mode = 3, ACTIVE
              - Analog / Closed-loop

Configuration of homing:
(Active and Passive configured in the same way)

Application:

Car moving on a track with one reference sensor at the reverse end of the track. There are three application positions: start, midway and end.

Observation:

Triggering ACTIVE homing with the MC_HOME instruction will execute movements to search the reference position.

For the case where the car is in a reverse position
with the sensor is already triggered.

The car will move forward first to clear the sensor. Thereafter the car will move reverse again to find the reference position. This behaviour is different than in earlier Motion Control versions (V3?) and fixes an problem.

The movements for the application are:

1.  fast-homing-speed forward to clear sensor
   
   
2.  fast-homing-speed reverse to activate sensor
   
   
3.  slow-homing-speed forward to clear sensor
   
   
4.  slow-homing-speed reverse to activate sensor
   
   

Irritations:

The change over of directions are too quick and causes mechanical strain. I need to investigate on forcing different ramping profile onto the homing routine. I suspect some other factors beyond user control also.

It would have been move effective if steps 2 and 3 could have been skipped. Even with the travel distance on step 4 is more, the overall sequence duration would be less and less mechanical strain.

Problem:

By pure accident my program repeatedly triggered the active homing as soon as #AXIS.StatusBits.HomingDone became active. (My mistake - not the fault of Siemens.)

After doing the sequence (1-4) correctly for several times, something goes wrong.

The movement gets stuck on sequence step 1. It continues forward direction until hitting the mechanical forward limit.


May this post be a notification to those who use MC_HOME.

BR

Hi

I0.5 Input filters?

SAR-CNT

Hi

I0.5 Input filters?

^{..{why the question?}}

MC_HOME is doing its task, yet there is still room for improvement. Summation from previous posting, the improvements could be:

• less sharp stop before direction change
  
  
• small delay before direction change
  
  
• ensure movement to move car off the sensor, does not move too far.

Hello, #dP

it may be necessary to adjust and speed before the movement ....

Hello.

SAR-CNT

Hello, #dP

to change the jerks and smooth running, I did the following:

Before the beginning of the movement, the acceleration and deceleration was corrected through the function MC_WriteParam...

it may be necessary to adjust and speed before the movement ....

A worthy suggestion. Many thanks.
I prefer using (see picture).

The problem is that the movement away from the sensor and the movement onto the sensor should have different deceleration rates. Forcing that onto the MC_HOME is not going to be possible.

The best way to handle this is to create a custom homing routine built on passive homing. Up to yesterday my custom designed used before did not work for Motion Control V6. The problem is being worked on right now.

BR

Hello, #dP

good decision...

SAR-CNT

tell me how quickly you can write values through the function MC_WriteParam?

 Your question is unclear.

recording time: 

MC_WriteParam.Busy to MC_WriteParam.Done,