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Quad Encoder with 1426, reverse direction

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Hi,

 

I run into a funny problem. I am using a PCI 1426 board (long story, it must be in a PCI machine, no PCI Express) with a line camera. I supply a quad differential encoder on the encoder input. So far so good. It even works as long as I move the axis forward. Unfortunately, I have to take images in both directions.

 

It would be trivial to solve this if I could set the encoder input polarity. Unfortunately, this is not supported on the 1426. The encoder scale is unsigned so something like scaling by -2 is not possible, either.

 

The encoder is a real encoder, thus, I can not change the polarity/direction in real time from software.

 

Is there any way out? Sure, I could add some electronics that can change the polarities in real time but that would be a last resort...

 

A less critical quation: So far this only worked using the external trigger output of the board (wiring it to the trigger input of the camera).  It would be nicer to trigger over the camera link CC1 line. I tried

 

imgSessionLineTrigSource2(Sid, IMG_SIGNAL_SCALED_ENCODER, 0, IMG_TRIG_POLAR_ACTIVEH, 0)

 

but  it does not work (using the "Trigger Each Line with Encoder" example project). Using imgSessionTriggerDrive2 in the same code I could send triggers, based on the encoder to the external lines. Am I missing something obvious? This is not mission critical as the trigger cable is already in and it works.

 

An alternative is to configure CC1 line source to External Trigger 0 but in that case what is imgSessionLineTrigSource2 supposed to do?

 

Thanks,

 

Gyula

 

 


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