Thermocouple Measurement with PXI2527 switch & PXI4071 DMM

[Riyad12]

I have tried to get 6 thermocouple reading using Niswitch Thermocouple measurement.vi (hardwares are PXI2527 &PXI4071). When I run the program with scan list Ch0:5->com0; the program is working but the relays are frequently switching On &Off. I am wondering it would reduce the lifetime of relays.How can I get the data with holding up the relays? I am currently using labview 8.5.Thanks

[johnsold]

According to the specifications the mechanical lifetime of the relay is 1E8 cycles but the electrical life at low current is 2.5E6 cycles. That is about one month at 1 cycle per second.

There is also a calculation of the errors you can expect when using thermocouples.

Lynn

[Riyad12]

Hi, how can I manage to hold the switches in ON position for a specific time?can DMM take data for all channels at a time?

[_kb]

Hi Riyad12,

The DMM only has one channel, so only one measurement can be taken at a time.

You can set the Scan Delay property to add a pause between execution of scan list entries.  As you put it, this will hold the relays in the connected state for a specified period of time.