rs232 sense line for event driven signal

[TunaFish]

Hi,

My vendor specification states:  "If utility power fails, the UPS sends a signal by bridging pins 8 and 5 through a RS232 interface." I am trying to setup labview to sense this signal through the RS232 interface. Is it possible to do this? It doesn't seem like a common RS232 protocol.

Thanks,

Tuan

[Dennis_Knutson]

You can use a VISA property node for the serial control lines (8 = CTS). When grounded, it should return an 'undefined' value.

[TunaFish]

So I tried your setup and keep getting 'Unasserted' as an indicator. Also note, I do not have the device with me, so all I did was jumper pin 8 and pin 5 together in a cable to see if there is a response.

In order for a value to change, do I have to apply a signal (voltage) to pin 8 to have it change to 'Asserted'? My pin 8 is currently just floating.

[Dennis_Knutson]

Floating to what? The asserted and unasserted states are valid and neither are gnd. You don't get 0V on a scope when the pins are shorted?

[Dennis_Knutson]

Sorry, CTS is the signal from the UPS. Are you shorting pins at the pc side? That would not be a correct emulation.

[TunaFish]

Well, I did a loopback test by using the RTS signal (pin 7) and inputing it into the CTS input (pin 8). When RTS is asserted, the CTS input shows that it is asserted. When I short CTS to the ground (pin 5) input of the PC (may not be the right way to do things), the CTS input show that the signal is Unasserted instead of Unknown. 

I am still waiting words back from the vendor to see if they have any signal in pin 8, but as of now, I have figured out how to setup this monitoring system. Thanks a lot for your help.