PXI4461 triggering problem

[KevinLilian]

Dear all,

I have a problem to generate analog voltage signal from PXI 4461 under analog trigger mode.

Basically, the triggering signal is generated by PXI 6221. The triggering signal is connected to the terminal AI0 in PXI 4461. 

The triggering mode is set at Start Analog Edge. When I run the vi, I received the error message as shown in the following graph.

The idea of this vi is very straightforward. I am wondering anyone could help me figure out what is going wrong there?

Thank you very much

Kevin

[LindyHop]

Hello KevinLilian,

The PXI 4461 does not support triggering an analog output task off of an analog trigger. You can still use a digital trigger for an analog output task.  

[KevinLilian]

Hi, Jonathan,

Thank you very much for your reply. However, based on the PXI 4461 supporting material, it looks like this device actually support the analog triggering. 

Clue 1: http://sine.ni.com/ds/app/doc/p/id/ds-337/lang/en

Triggering

NI 446x devices offer both analog and digital triggering for signal acquisition. The source of the trigger can come from any analog input channel, the external digital trigger input, the PXI trigger bus (PXI devices), or the RTSI bus (PCI devices). The external digital trigger is 5 VTTL/CMOS-compatible and is activated by a choice of rising or falling edge. Triggering is needed in applications that acquire transient signals. When performing structural analysis by striking a metal beam with a hammer, for instance, you measure transient vibrations with accelerometers with acquisition triggered by the hammer impact. 

Clue 2: PXI 446X specification pdf

Actually this is where confuses me. Because if the device do support analog triggering, I should not receive the error message.

Thank you

Kevin

[AJ_CS]

May be Analog triggering is applicable only for acquisition, not for AO generation. If that is the case, I am also curious to know as to why that difference is there.

What will this AO that you generate be fed to? 

[KevinLilian]

Hi AJ_CS,

The AO generated will be connected to PXI 4498 for data acquisition. Right now this is an idea testing stage. 

Thanks

Kevin

[LindyHop]

Hello KevinLilian,

The manual for the 4461 is currently very misleading. A documentation Corrective Action Report (CAR) has already been filed to have it clarified. An analog input task can be triggered be either a digital or analog trigger. An analog output task can only be triggered by a digital start trigger.

[KevinLilian]

Hello Jonathan,

Thanks for your information. Please correct me if I am wrong. Based on my understanding, If I want to apply external digital triggering signal to control the analog signal generation from PXI 4461, the digital triggering signal could only be imported into the device through SMB terminal. Am I right?

I am also wondering if the analog triggering signal is a steep pulse (5V), what will happen if I let it pass through the SMB terminal? Could it achieve a similar effect? Will it damage the device?

Thanks

Kevin

[LindyHop]

Hello KevinLilian,

You can use PFI0 to route the digital signal or you can use the PXI backplane and use PXI_Trig<0..6>. Theoretically you could you could send a sharp analog pulse and trick the program into thinking its a digital rise but I wouldn't recommend it.