How many quadrature encoders can be read simultaneously with the cDAQ-9188 chassis?

[jtrout]

We may need to record position periodically of 8 motors (at the same time that we sample corresponding analog inputs).  It looks like the 4 built-in counters limits the chassis to 4 encoders.  Is this correct?  I am familiar with PLC counter modules that handle the high-speed counting, and then the CPU periodically poles for an update of the total counts.  Is this how the NI 9401 card would work?

[Stop_Luke_and_Listen · Accepted solution]

Hi jtrout,

You are correct that the 4 built-in counters limit the cDAQ-9188 chassis to 4 encoders.  The following article discusses using the NI 9401 card for encoder measurements: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1riCAA&l=en-US.

[jtrout]

There's not much in the budget for this project, so it looks like stepper motors without position feedback are the way to go.  I'd feel better with encoders to confirm the position, but steppers are used open-loop all the time.  Our preliminary tests with encoder feeback are showing that we don't lose steps, so the encoder may be redundant.