What hardware do I need to monitor the signal from an incremental encoder?

[CE185]

We are trying to implement a feeding solution for one of our cutting machines and I’m not quite sure how to proceed.  I have attached a document from the NI website that outlines exactly what we are trying to do but does not go into detail on any of the concepts like programming and implementation.

1.) We have a NI DAQPad-6015 connected to a SC-2345 which has one SCC-CTR01 module installed.  Which this configuration can we read the incremental encoder signal and use to setup our cutting machine as outlined in the attached document?  If not what is the minimum amount of hardware we need to sample the signal from the incremental encoder and obtain both the direction and magnitude of the movement?

2.) If we wanted to use the information obtained from the encoder and subsequently send a signal to a stepper motor controller or perhaps a PLC what additional hardware would be needed.

Thanks,

Chris  

[Jochen]

Hi Chris,

1. For quadrature encoder measurements your hardware is not the ideal equipment. The 6015 doesn't provide X4 decoding. That means, that the board counts only one raising edge of one phase. Still, if you connect phase A and B to the counter inputs, it will count up and down, depending on the direction of the axis, but as already mentioned, you will loose 75% of the available resolution. 
   The document that you are referring to recommends a PCI-6624 and this is in fact a much better option. This board provides X4 decoding and isolated inputs not only for phase A and B but also for the Z-index (not available for the 6015).
   
   If you need a USB-solution and if you can work with TTL voltages, you might have a look at the USB-6218, that provides isolated I/Os.
2. For motion control there are various options. E. g. you could use an NI motion control device like the PCI-7332, but there are also options to communicate with external motion controllers through CANopen, RS232 or various fieldbusses. Depending on the solution that you choose, you may need a bus interface that provides support for your programming software.

I hope that helps,

Jochen Klier

National Instruments

Message Edited by Jochen on 09-24-2008 09:24 AM

[CE185]

Thanks for the info.  I will continue to research my options.