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ericc

Posts: 2
Registered: 05/29/12

Using 34901A module to scan AND switch - battery discharge testing
Posted: May 29, 2012 1:24 PM

34970a , expert , logger , switch , 34901a , datalog

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I'm trying to use a 34901A module in a battery discharge test. I have one channel set up to measure Voltage across the battery and another channel to measure Current out.

My question is, is it possible for me to have it automatically switch off the current once I reach a certain voltage threshold? I need it to open the current and open the circuit once the battery has been discharged to a certain voltage (so I don't damage the battery)

I have been doing this manually, but there is no audible alarm on the 34970A module (or I have been setting it wrong) and I been missing it.

thanks in advance for your help!

Edited by: ericc on May 29, 2012 2:21 PM

tomc

Posts: 118
Registered: 01/12/11

Re: Using 34901A module to scan AND switch - battery discharge testing
Posted: May 29, 2012 3:49 PM

in response to: ericc

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There are a couple of ways to do this. Each requires a program running in a computer evaluating the alarm status and opening a channel to stop the current. One way would use a separate 34903A GP relay module for the current switch. The other would be to use a channel on bank 2 of the 34901A if it's not already being used. I wouldn't actually use alarms for this since the DMM has to make a measurement each time anyway, just have the computer program scan the channels, test the values and open the channel when the setpoint (in the program) is reached.

ericc

Posts: 2
Registered: 05/29/12

Re: Using 34901A module to scan AND switch - battery discharge testing
Posted: May 29, 2012 3:57 PM

in response to: tomc

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But basically, either method would require a second module? I guess my real question is if it's possible to do it from that single module (since that's all I have access to)

tomc

Posts: 118
Registered: 01/12/11

Re: Using 34901A module to scan AND switch - battery discharge testing
Posted: May 30, 2012 9:06 AM

in response to: ericc

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The 34901A has two 10 channel banks that can be operated independently of one another. Bank 2 is isolated from bank 1 by relay channel s99 (199) for the 34901A in slot 1. If you use open and close commands to close the individual relays and the MEAS command without a channel number, you have full control and can keep bank relay 199 open. Then you can close any channel on bank two to connect it to the bank 2 common. I will double check to see if channel 199 stays open until you address a channel on bank 2 for a normal measurement command sequence. If so, you won't have to change any of your measurement commands. You can do this yourself by trying it an querying the state of channel 199 with the ROUT:CLOS? (@199) query.

tomc

Posts: 118
Registered: 01/12/11

Re: Using 34901A module to scan AND switch - battery discharge testing
Posted: May 30, 2012 9:59 AM

in response to: ericc

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I take it back. I was confused by the way the 34980A works. The 34970A closes the bank relay and opens all channel relays on both banks whenever you do a measurement on any channel. So there is no way to do this with only one 34901A.

bebop75

Posts: 3
Registered: 01/18/13

Re: Using 34901A module to scan AND switch - battery discharge testing
Posted: Jan 18, 2013 9:49 AM

in response to: tomc

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Sorry for reopening this old post
But i have a concern about this reply and could be also helpful to others.
Why you not recommand to use alarms with TTL logic to do that?

Thread: Using 34901A module to scan AND switch - battery discharge testing