Why Doesn't My SCXI-1192 Work Properly After Performing Multiple Relay Operations?Hardware: SCXI>>Modules>>SCXI-1192
Problem: Why doesn't my SCXI-1192 work properly after performing multiple relay operations? How long do I need to wait after switching a relay on the SCXI-1192 before I can switch it again? Solution: The SCXI-1192 18 GHz switch module has a relay reactivation time (the amount of time you need to wait after switching a relay before you can switch it again). This reactivation time is required to discharge the pulse circuit for the latching relays. For the SCXI-1192, the reactivation time is 500 ms. The actual delay required to reliably reactivate a switch will vary from relay to relay, and may be as low as 50 ms in some cases. However, for guaranteed operation, you should wait a full 500 ms. Microwave measurements are often fairly slow, so the relay reactivation time is usually not an issue as long as it is accounted for in your application. If you do not account for the relay reactivation time and the relays are instructed to switch too quickly, they may fail to actuate. To recover from this situation: 1) Wait 500 ms. 2) Send a command to actuate the relay back to its previous state. The relay itself never moved from this position, but sending the command gets the software state back in sync with the relay position. 3) Wait 500 ms. 4) Send a command to actuate the relay forward again. This time, the relay should actuate as instructed. The relay reactivation time can be accounted for in your application by adding a 500 ms delay in between all relay operations. For example, you should add a 500 ms delay between the "niSwitch Initialize with Topology" function, which resets all of the relays by default, and the "niSwitch Relay Control" function which operates a relay. In LabVIEW, you can insert a delay by inserting either the Wait (ms) function or Time Delay function within the Time & Dialog subpalette of the Functions palette. For additional clarification, the 15 ms relay operate time specified for the SCXI-1192 is only the time that it takes for the relay to physically change states; it does not account for the time needed for the relay to prepare itself to receive a command. The relay reactivation time is the combination of the time it takes for the relay to physically change states, and to prepare itself to receive a new command. Related Links: Attachments:
Report Date: 10/22/2003 Last Updated: 10/27/2003 Document ID: 32LEPSCW |
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