Digital I/O

cancel
Showing results for 
Search instead for 
Did you mean: 

NI 9476 maximum switching speed

Hi everyone,

 

i have a cRio with a NI 9467 Digital Output Module and i am trying to generate 30-100ms wide pulses every X ms to simulate a s0-interface used by electric meters (not the S0 interface for ISDN). The pulses, high or low are specified to be at least 30ms.

The problem is, that the pulses only occur every 100ms. When for example the length of the pulses is changed to 160ms, the pulses switch randomly between 100ms and 200ms as you can see in the pic. The same happens if the off-time isn't a multiple of 100ms.

The vi is made in LabView 15.1

 

The Update Rate is given by 500µs (with high and low period 1kHz max.) so this should be no problem or do i understand something wrong?

Is it possible to configure the Update Rate?

 

 

regards,

Mathias

0 Kudos
Message 1 of 5
(4,263 Views)

"I have a cRio with a NI 9467 Digital Output Module"

 

I think you mean a cRIO with a NI 9476 like the topic of this discussion says.
I'm right? By the way, which cRIO do you use?

 

 

"When for example the length of the pulses is changed to 160ms, the pulses switch randomly between 100ms and 200ms as you can see in the pic"

 

Why do you change the length of the pulses to 160ms? You said you want to generate 30 - 100ms wide pulses. You do that only to show this behaviour?

When you set the length of the pulses to lets say 60 ms, what's the result? Could you please post a screenshot of that?

0 Kudos
Message 2 of 5
(4,188 Views)

Hi Maxe,

 

first of all, thanks for your reply.

Yes, its a NI 9476 Module, used within a cRIO-9066.

And yes, i changed the length of the High-Pulses to several different values between 10 and 500ms to see if my assumptions are right that it only switches at a multiple of 100ms.

 

I attached the pics you wanted.

 

regards

0 Kudos
Message 3 of 5
(4,124 Views)
0 Kudos
Message 4 of 5
(4,055 Views)

Hi,

 

 

the NI-Support gave me a really easy solution!

You can configure the Scan-period of the Scan Engine, which is 100ms by default. I changed it to 1ms and it works just fine.

 

To change the scan engine period, you need to rightclick on your target in a project, select properties and choose the Scan Engine Option from the categories.

 

 

My problem was, that most of the options in the properties were not displayed because my software wasn't installed in the correct order (due to the support).

 

Correct order:

1.) LabVIEW Development System
2.) LabVIEW Real-Time Module
3.) LabVIEW FPGA Module (recommended)
4.) NI-RIO driver

So, after reinstalling everything, the options appeared.

 

 

regards,

 

Mathias

0 Kudos
Message 5 of 5
(3,966 Views)