HPLC pump feedback control

[siew]

Hi,

I am currently trying to control the flow rate of a Merck-Hitachi L-6200A HPLC pump in response to the liquid level in a tank, given by an ultrasonic level sensor.

The ultrasonic level sensor gives a level reading communicated through a DAQ. I have taken this reading and used simplepid.vi to produce an appropriate change in flow rate needed.

To change the flow rate <FLOW> on the pump, I need to enter the following string ''MANUAL <FLOW> 400 0\r''. The VI is able to produce this string in response to the changes in liquid level. However, I have been unable to communicate this command to the pump using the subVI pump protocol. When I activate subVI pump protocol alone, it is able to transmit the command to the pump and change the flow rate. The non-transmission problem arises when I run the whole control.vi.

Is it a problem with the simplePID.vi producing an output much faster than the pump protocol vi can transmit to the pump? Or is there a more fundamental problem with my programming? Would appreciate the help.

Cheers

[johnsold]

You are not sending a carriage return to the pump controller.  You are sending a "\" character followed by an "r" character.  To use the backslash codes for non-printable characters, you must enable '\' Codes Display on any string control, constant, or indicator.  The "400 0\r" string constant in control.vi has this set to "Normal Display."

Lynn

[tlcollier]

I am trying to ontrol the same pump using Labview. I do not have the current version of LAbview so I cannot load your example .vi.

Can you tell me what commands to send to set the flow, composition and read back the pressure?

Thanks

[johnsold]

The original poster has not been on the Forums for more than two years. The VIs he posted do not contain the commands so you will need to check the documentation for the pump controller.

Lynn

[tlcollier]

I was given the pump but there is no manual with it and I am trying to incorporate it for a student project for them to learn some programming.

I was hoping someone on the string would have the commands.

Thank you for your response.

Lee

[Agostinho84]

Hi there!

i´m currently trying to recover an old pump just like that but i cannot find the manual!

by any chance do you have it? can you upload a copy please?

Thanks!

best

A.

[tlcollier]

Hope this is the one you are looking for.

[tlcollier]

L6200 instruction manual

[Agostinho84]

Thank you so much!!!

Have a nice week!

Best

A.