How many encoders can you connect to NI9411

[QianBath]

Hi all, 

Is it possible to connect two encoders to NI9411? We are using linear quadrature encoder, at the moment DI0a/b, DI1a/b,DI2a/b are used to connect the A, B and Z input for one encoder. Then we have DI3,DI4,DI5 pin left. I look at the DAQmx Channel, it seems it is not possible to define A,B and Z input separately for two encoders. Is it right 9411 can only take in one encoder or am I missing something when I try to define the A,B and Z input for two encoders?  

Thank you in advance, 

Qian

[GerdW]

Hi Qian,

the NI9411 is just a module: which chassis do you use?

I guess you can do all kind of counters using the FPGA in a cRIO chassis, consuming all DIs of your module…

[rolfk]

---

@GerdW wrote:

Hi Qian,

the NI9411 is just a module: which chassis do you use?

I guess you can do all kind of counters using the FPGA in a cRIO chassis, consuming all DIs of your module

---

If you use a cRIO, then yes. You can program as many biphase decoders in FPGA as you wish (well at some point you might get problems with not having enough gates, but that would be for much more encoders than what you could connect with one 9411 module.

With a cDAQ chassis things get much more restrictive. The 9411 is just a digital IO module and does not contain any sort of counter logic. The backplane of a cDAQ chassis has a limited amount of counters available. How much that is depends on the actual chassis and can be seen here:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019MFFSA2

There is somewhere also a document that lists the cDAQ-913x chassis too, which I believe support also 4 counters.

Not all C series IO modules can access the counters on the backplane in order to be used as counter input:

https://www.ni.com/en/support/documentation/supplemental/18/cdaq-module-support-for-accessing-on-boa...

[QianBath]

I use cDAQ 9174, sorry forgot to mention it. 

[QianBath]

Hi rolfk, thank you for the detail explanation. We use NI9411 with cDAQ 9174, it works with one encoder. so I guess it can access the counter on encoder. Is it possible to know how many encoders can connect to NI9411 for this perticular cDAQ?  

[rolfk · Accepted solution]

It also depends on the encoder you use. But I'm sure it can do two encoders, maybe even four but that is it, no matter how many 9411 you would put in the chassis.

And you won't be able to do other things in parallel such as continuous analog input and/or analog output as that needs normally counter/timers too for the clock generation of those operations.

[QianBath]

Hi both, we got it working for two encoders at the end. I can see four counters appears on the input, so I assume that it means we can connect 4 encoders theoretically. I don't know why I assume that I cannot create two channels in the Labview code for one module, but apparently I can and it works. Thank you very much for your help again.