Shift Active CamIn

Morning everyone,

I am currently working through my first Motion Control project and was looking for some advice regarding the MC_CamIn instruction. I am using TIA Portal V15.1 and S210 servo drive for the synchronous axis. To give some background, the machine has an External Encoder mounted to a main drive shaft, the Encoder position is used to trigger Output Cams and provide reference for a Synchronous Axis cam. The Synchronous Axis is a Pinch Roller which pulls a set material length through the machine based on recipe settings.

As an example the recipe and subsequent Cam is configured as follows:

Point1.x = 0.0, Point2.x = 1.0, Point3.x = 68.0, Point4.x = 360.0

Point1.y = 0.0, Point2.y = 0.0, Point3.y = 180.0, Point4.y = 180.0

The master axis is set up with Modulo range 0.0 to 360.0, the slave axis is linear. The above example would Cam the Pinch Roller to pull 180mm of product between 1.0 and 68.0 on the master axis. I have configured the CamIn instruction with SyncProfileReference = 2 and this works fine when I Interpolate and execute the CamIn at standstill (machine idle).

I have been thrown a curve ball, the client needs the facility to adjust the Cam positions (both master and slave) while the machine is running. The reason for this is a sealing bar and cutting knife are mechanically cammed to the main shaft, to ensure the knife cut is always in the center of the seal we need to allow the operator to make fine adjustment to the pull through start and end psoition. Unfortunately stopping the machine for adjustment is not an option.

After looking through the documentation I am unable to find a solution to this. Any help would be greatly appreciated.

Hi Mister T,

Thank you for getting back to me on this. Chapter 7.8 of the "Comparison of the Synchronization Modes" seems to have the information i was looking for. Just a few follow up questions.

1. If Cam 1 is "In Sync", the Cam 1 Execute input is false and the machine is running, to sync Cam 2 all I need to do is provide a rising edge at the Execute input?

2. Will this synchronize the Cam to the positions stated in the Cam profile or will the Cam be offset based on the actual position of the External Encoder (master axis) when the Execute request is given?

My worry is that if I have configured Cam 1 as follows:

Point1.x = 0.0, Point2.x = 1.0, Point3.x = 68.0, Point4.x = 360.0

Point1.y = 0.0, Point2.y = 0.0, Point3.y= 180.0, Point4.y = 180.0

If Cam 1 is synchronized at standstill with actual position of the External Encoder = 0.0 it will sync with no issues, if I then execute Cam 2  where Point2.x = 2.0 and Point3.x = 69.0, if the actual position of the External Encoder is 150.0 when i give the execute command will Point2.x and Point3.x be offset by the Encoder actual position i.e. 152.0 and 219.0 respectively?

Many Thanks.

Hi Mister T,

Thank you for your help in resolving this and for the reference material.

I have created some logic to monitor the recipe values for an on the run change, when a change is recorded I populate a Pending Cam with the new point data, this is then interpolated and synchronized as the Working Cam at the beginning of the next profile. The previous Working Cam becomes the Pending Cam when the synchronization process is complete (InSync).

I have the Cam configured with profile reference 1 and application mode 2 ,where I was having difficulty is with appending the data. As I am using a half Cam whenever I create a Pending Cam the Slave Offset needs to reference the actual position of the synchronized axis. With this in place everything is working perfectly.

Thanks again