Controlling two cDAQ-9181 from one ethernet port using an ethernet switch

[ryham]

I'm running a program that uses a 9213 analog input module along with a 9474 digital output module. The input module collects thermocouple data with ADC timing mode set to high speed. At first, I was using a 4 module cDAQ-9185 to collect this data while also outputting voltage from the 9474. I recently switched to using two cDAQ-9181 devices, each holding one of the two modules and connected to the computer using an ethernet switch, and I noticed that the program lags and slows down a lot whenever the output module is used at the same time as the input module. This problem never occurred when I used the 4 module cDAQ-9185. Is there any way to fix this so I can use the two 9181s without lag or slowness?

[ZYOng]

Instrument Bus Performance – Making Sense of Competing Bus Technologies for Instrument Control

Ethernet communication has the worst latency at the milliseconds level. Adding a network switch to route the packets increase the latency further. If you want to have low latency, you should use a cDAQ with its own controller (cDAQ-913x) or USB cDAQ (cDAQ-917x).

[ryham]

Thanks for the reply. Although this may be the case, I believe that there is another issue occurring. The time delay is only occurring on the analog input module and it is taking a full second to read the thermocouple temperatures even though the ADC timing mode is set to high speed. Again, this is only happening when used in sync with the digital output module. Even when both cDAQs are connected, the speed is fine as long as only one module is being used.