Switch to DMM connection - handshaking/scanning necessary?

[jinjupk]

Hi,

I'm wondering why handshaking or synchronous scanning is necessary. Instead, wouldn't it be possible to make connections on the switch then read data directly from the DMM (attached below)?

What I want to do is use the switch to connect two points, have the DMM start reading the four wire resistance values between the two points, wait a few seconds, then acquire several samples. The key is that I want the DMM to be activated for a few seconds (sending current to find resistance) so that the resistance value settles before my program gets the resistance values.

With the DMM Switch Synchronous Scanning example program, it seems like the DMM only reads values when triggered by the switch, which I don't think is what I want. I may be understanding this state diagram incorrectly, though. What exactly is the idle state for the DMM (attached below)?

Thank you,

jin

[crossrulz]

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@jinjupk wrote:

What I want to do is use the switch to connect two points, have the DMM start reading the four wire resistance values between the two points, wait a few seconds, then acquire several samples. The key is that I want the DMM to be activated for a few seconds (sending current to find resistance) so that the resistance value settles before my program gets the resistance values.

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Then just do that.  You don't want to use the handshaking/scanning feature.

1. Initialize the DMM and the Switch

2. Make the connection you want to measure

3. Wait your 2 seconds

4. Take the measurement

5. Disconnect the switch connections

6. Repeat 2-5 for as many connections as you want to test (think FOR loop here)

7. Close the DMM and the Switch drivers