Detect if shutdown input is active PCI-733x

[ben64]

Is there a way to detect if the shutdown input of a PCI-7334 controller is active?

I'm using LabVIEW 2011 SP1 and NI-Motion 8.3.0.3 and there doesn't seems to be a function that read the state of this input. The setup controls 4 stepper motors and include an UMI-7774. An emergency stop pushbutton is connected to the global stop input of the UMI. No feedback devices are used, the steppers are in open-loop.

Basically what I want to do is make sure that the emergency stop pushbutton is not pressed before starting a test, if so the start test command is cancelled and popup message is displayed asking to check the state of the pushbutton.

The controller shutdown is activated by a rising edge on this input, so if a test is running it will immediately stop but if the pushbutton is already pressed when the test start the controller will send the steps and direction signal to the drivers. Note that the motors will not run because the drivers are disabled by the emergency stop pushbutton and that the controller will eventually stop on a programmed error condition but it is a non-negligible waste of time.

A possible workaround is to also connect the pushbutton to a digital or analog input on the UMI but it seems odd to me that the state of this input can't be read.

Any other suggestion?

Ben64

[Simon-P]

Greetings;

After some preliminary search, I have not come across any VI that would simply check the value of the Shutdown line on a 7334. While I came across a few articles on implementing an Emergency stop, nothing popped up for that particular matter. 

My initial thoughts are that the best way to go about it would be to simply split the wire into both the Shutdown line as well as any DIO input and check it therein. I will, however, do some more research and inform you of my findings.

Cordially;

Simon P.

[ben64]

Thanks Simon.

Ben64

[Simon-P]

Greetings, Ben;

I have done some more research on the matter, as well as discussed the matter with a few of my colleagues. While there is a VI that will allow us to toggle whether the system will react to the signal in the shutdown line (Enable Shutdown). I have not, however, found a way to simply monitor what is in that line without requiring a secondary connection.

Cordially;

Simon P.