Control of HM 7044 with Lab View

[ronsmagic]

hey people I am trying to control a Hameg 7044 power supply with LaBview using a serial RS 232 interface..... I have the basic programm with me but i have no idea how to write into the string buffers and how to read from the read strings....if any of u people have worked with this power supply earlier and could help me out i would be highly grateful....because right now i just can not send any commands to the instrument and cant read any data from the instrument as well

[Dennis_Knutson]

There is a driver for that here. Check the main Instrument Driver Network for information on what a driver is and how to use one. I would also recomend that before you do any LabVIEW work, verify the serial connection with a program like Hyperterminal. This will verify the com port settings and the cable is correct. If you cannot read or write with Hyperterminal, then you will not have any luck with LabVIEW until you fix it. A large number of serial instruments come with Hyperterminal instructions and you can almost certainly can get help from the vendor when you have issues.

[ronsmagic]

thank you dennis,

                               I have already downloaded the driver from the Hameg website...and i also tried to check the serial connection with Hyperterminal ......the thing is that the port does not deliver the desired results with Hyperterminal programm(is it because there is no internet connection in the PC?) but it works fine with the loopback.vi...i dont know what this could be due to....even i thought that the port was out of order after i ran the hyperteminal programm and i kept gettin the message "port could not be opened"....but after testing it with the loopback.vi and gettin the positive result i am not sure what the real situation is.....what do u think ??

[Dennis_Knutson]

The internet has nothing at all to do with a serial connection to an instrument. A serial loopback test does nothing more than verify that the com port on the pc is functional. It does nothing to verify that you have matched the com settings on the pc to the com settings of the instrument. It does nothing to verify that you have the correct cable between the pc and instrument. There are two types (null-modem and straight-through). Check the manual to see what type you need and use a continuity checker to verify that the cable you actually have is correct. It sounds like you tried to open Hyperterminal while the LabVIEW VI was open. You can only have one open at a time.

[ronsmagic]

hmmm.... thanks again.......but im a bit lost.......the instructions on the ni.com website do not mention anything about connecting the wire to the port for conducting the hyperterminal test... i just carried out the test as per the instructions without connecting the cable or the instrument.....i dunno mightve been a mighty foolish thing to do.....but i guess u might be right about me doing the hyperlink test while the labview vi was open......

[Dennis_Knutson]

I don't know what Hyperterminal test you are refering to. I found this and you most certainly have to have something connected to the pc's com port in order to run. And my main point is that since you do not connect the instrument or the cable you use to connect the instrument to the pc, you've not tested much of anything except the pc. You still have to do the basic troubleshooting I mentioned. Have you done any of this?

[ronsmagic]

hello dennis,
                    Thanks a lot for your inputs.... i carreid out the test as advised by you and luckily the port is workig fine and i can communicate with the instument. I am also using the driver for HM 7044 for programming the power supply...the thing is that the stand alone programm for switchin on and off the power supply is just working fine but when integrated with the main temp control program the power supply is not being controlled. i dont know for what reasons this could be.. I will attach both the programs in my next message and perhaps u can have a look at them and tell me where i am goin wrong.....

Cherio

Ron