Instrument Control (GPIB, Serial, VISA, IVI)

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Labview difficulties with Harvard Pico Plus pumps



I am having difficulties controlling Harvard Apparatus 11 Pico Plus model pumps. I am using Labview 8.0 and the latest release (10/05) of the Harvard Apparatus Pump 11 Series drivers.


Specifically, my problem is with the sub-VI entitled "Read Flow," which calls VISA Write during its run. When it attempts to write something to the pumps, an error is returned. "Special" then comes after it, and also returns an error.


"Configure Flow" also calls VISA Write and Special Read, but works fine. And as far as I can tell, all the other calls of VISA Write and Special in other programs work fine.


I've checked all the connections between my pumps and the RS-232 PCI card with 4 serial ports through which I connect them to my computer. I've made sure that baud rates (9600) and stop bits (2) all matched on the pumps, in Labview, and in Windows device manager.


If anybody could guide me in the right direction, I would greatly appreciate it. I'll post pictures of the code for "Read Flow" and "Configure Flow" soon.




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Message 1 of 7
I recomment that you confirm you are using the lastest firmware for that instrument.  I am aware that some improvements were made in the latest version of firmware that impacted remote communication.
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Message 2 of 7
Are you still having difficulties with the instrument? If not, try testing the "Start Pump" VI and see if it is working properly or not. It would also help if you could explain the order in which these VIs are being called. Good luck!
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Message 3 of 7
To add to Jason's comment, I've tested the Read Flow Rate VI on a Harvard Apparatus 11 Plus, and it works properly on my computer. The instrument firmware revision that I am currently using  is 11.062. You can observe the firmware version using the Revision Query VI.
Message 4 of 7
Thanks for your suggestions, both of you.

Unfortunately, Revision Query VI is itself having a timeout error when I use it.

To fulfill my earlier promise, here are screenshots of the relevant programs. I now believe the error lies within either Read Flow Rate VI, Special Read VI, or Read Range VI. Here are more detailed observations concerning the problem to help others make sense of it.

When Read Flow Rate VI attempts to receive information from the pumps using Special Read VI, an error occurs:

Possible Reason(s):
(1)  Timeout error

Sometimes this happens because Labview's VISA write command attempts to send a message to the pumps, but fails. Other times, the error
begins with Special Read VI itself. When the VISA Write command makes an error, the message returned is that below:

VISA Write in Harvard Apparatus Pump 11 Series.lvlib:Read Flow

The propagation of this error eventually reaches Read Range VI, which returns the following error:

Possible Reason(s):
(1)  Cannot find units

Read Flow



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Message 5 of 7
When you are having problems using instrument drivers, I would try using
Hyperterminal to communicate with the instrument.

Also locate the manual containing the commands for the instrument.

Try to send the command manually and see if you get an error.

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Message 6 of 7
I know the original post is a bit dated, but as someone who also was helping another user with a harvard pump, one thing to make sure of is that you are using the correct cable.  These pumps use straight through RJ11 cables, which are NOT the same as many phone line/modem cords, which corssover.  The cable ends should have the same pin out order (black, red, green, yellow; or RXD, TXD, GND, GND) on both ends.  These are availble at many electronics outlets or probably from Harvard Apps themselves.

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Message 7 of 7