Synchonisation of multipe different I/O modules inside a CompactDAQ Chassis

[T.Meyer]

Hello,

I´m currently using various different I/O-modules (e.g. NI9229, NI9203) inside the cDAQ-9184 chassis.

For setting it up and creating tasks im using the NI MAX software. These tasks are then used in DASYLab 13.0.

The problem im experiencing is a constant time delay between signals from different I/O-modules. No matter what sample-rate type I´m using, there seems to be an issue with the synronisation between those modules. From my understandings, the chassis should synchronise the modules via internal clocks but with different tests I got a constant delay of 1.6ms between the same rising or falling edge, measured from different I/O-modules at the same time.

Is there something I got wrong or should the chassis indeed synchonise the signals on its own?

Thanks in advance!

T.Meyer

[bhovhann]

Hi,

Did you make any synchronization? 

here you can find the way how to  Simultaneously Start Multiple Modules Using a cDAQ Chassis in SignalExpress 

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000PAbcSAG&l=en-US

[T.Meyer]

Hi,

since the cDAQ-9184 manual notices its capability of "up to 7 hardware-timed analog I/O, digital I/O, or counter/timer operations simultaneously" I chose to work with a Multidevice Task mentioned in your link. Maybe that was a wrong decision since it also recommends to not use it for different types of modules (not sure if that is relevant for 2 different AIs that I´m using). Since it´s one task there is no way to synchronise the signals afterwards in DasyLab.

Using a different task for every module causes immense delays up to 2sec. while I wasn´t able to enable an External Trigger in NI Max (solution 1 in your link, every option in the dropdown menu is grayed out). It seems that this solution also only mentions Digital I/Os while I´m only using Analog Inputs. A synchonisation via DasyLab wasn´t possible either, due to "different timebases" of the two tasks.

Solution 3 isn´t available with the chassis I´m using.

Those are the reasons I chose to put both modules into one task and use the OnboardClock as the internal sample rate. No other synchonisation because (I thought) the chassis should do exactly that via its internal clock. But this leads to my constant 1.6ms delay between the to signals.