Scan Engine & EtherCAT Custom Device Feedback

[rdkroupa]

Bingo.  Very similar names, I overlooked that.

Thanks everybody!

[Mr221]

I am having issues with a 9219 module in a 9144 EtherCAT Slave chassis connected to a PXIe-8840RT Controller in VeriStand 2014 with EtherCAT 14.0.  I have the module configured in High Speed Mode.  When I set a channel for 3 wire RTD and attach a sensor per the diagram, I get NAN as the value upon deployment.  I have also noticed that in Voltage mode, the reading is not scaled correctly.  I read about 6.5 volts when inputing a 10 volt dc signal.  I have also tried high resolution mode and seem to have the same issue.  Can anyone confirm that they have used the 9219 in 3 wire RTD mode with this custom device?

[Ryan_S]

Interesting, I haven't set that up myself but I would expect it to work; it's just a universal AI. A couple thoughts:

1. What channel do you have the RTD connected to and are the other channels wired? I know we've had problems with Thermocouple modules and open thermocouple detection, and I don't think the module or RIO do anything like that for RTD but moving this to channel 0 would be a way to check that...
2. The offset on the voltage reading is weird, what terminals were you connecting the + and - leads to?
3. Do you have a cDAQ chassis you can put the module in to run test panels on the static voltage? Maybe the module is bad?

[Mr221]

There was an earlier post about the 9219 not handling thermocouples correctly that never seemed to get answered. I wondered if it's possible that there are other issues with configuring this module..

We are working with channel 0. I have experienced the open thermocouple issue in the past so I'm careful to work with the first channel first.

For the voltage connection we are using Terminals 4 and 5. The voltage follows the input proportionally, it's just about 25% low.

We are using the recommended three wire red connection. Terminals 3,5, and 6. I don't suspect a wiring issue since we are getting NAN for a reading. That seems to be more software related.

I wish I had a spare cDAQ chassis as well, I had thought about testing the module that way earlier. I do not though.

[Ryan_S]

Hmm, well I don't have an RTD handy (I can look for one on Monday) but I did do a quick voltage test using a 9082 as the EtherCAT master with the 9144 and 9219 hooked up to a virtual bench for DC voltage input. The AI readings from the 9219 matched (within 0.01 V) what was being output by the virtual bench. So It appears at least that the voltage reading should work....A couple thoughts:

1. Maybe there's some weird scaling being applied within your system definition file? If you open NI Distributed System Manager and look at the 9219 values do they match what's being output by VeriStand?
2. If the DSM values match the "wrong" VeriStand values then this may be an issue with the module. If they're different, then it could be something in VeriStand. Do you have a license of LabVIEW to try reading the values from the slave in LabVIEW to see if the difference persists? (i.e. take VeriStand and the custom device out of the equation)
3. Another option would be to drop the module down to the FPGA on the EtherCAT slave instead of using pure scan mode and send the values back up via User Defined Variables. If those still give you incorrect readings then I'm again going to lean towards a module problem. But you would need a LabVIEW license to try this.

[AGCOJason]

Hello,

I have a NI 9146 that I would like to access from a PXI based VeriStand project.  I wanted to find out if this custom device would work with the Ethernet RIO Expansion chassis?

Thanks

[Ryan_S]

Hey AGCOJason,

No, this custom device does not support EtherNet RIO Expansion chassis.

EtherNET RIOs  introduce determinism, synchronization, and other timing considerations/issues so they aren't something commonly seen in HIL systems. We'd typically go to a MXI RIO, R Series Expansion, or EtherCAT if you needed to add I/O to a PXI system.

However, if you're simply interested in seeing the data in your HIL system with a 9146 without the tming considerations, then you could look at just reading the I/O as shared variables using a custom device. Maybe something like this:

Shared Variable Custom Device

https://github.com/NIVeriStandAdd-Ons/Shared-Variable-Custom-Device

Hope that helps!

[AGCOJason]

Thanks,

I will check that out.  Since the 9146 is only being used for low speed readings (ignition turned on etc.) and the simuation is not impacted by a delay in the signals any latency in the input shoudln't be an issue.

Thanks

[Mr221]

Ryan,

Were you able to look at an RTD configuration with your setup?

[Ryan_S]

Hey Mr221,

Sorry for the delay, took me a bit to track down a spare RTD. I hooked it up (3-wire so 3,5,6) and am getting a reading. However, I don't know what type of RTD it is so I'm reading like 98 deg C. But, I am getting a reading compared to getting NaN. So I'm inclined to believe that everything is working properly.

Were you able to look at the values from the EtherCAT channels in Distributed System Manager? Any updates or thoughts on the other suggestions I posted?

I've also attached my sys def so you can see how my system is configured (it's very simple). Can you attach yours and I'll try running it on my end to see if there's any specific configurations that may be differing?