How can I read the voltage from a serial port

[bassboss]

I am fairly new to LabView and I am having trouble figuring out how to read the DC voltage coming out of an RF Power Supply through a serial port so that I can monitor the voltage every few seconds. In order to do this do I need to purchase a DAQ card or anything like that?

[smercurio_fc]

You would not need a DAQ card to read data over the serial port. You would, however, need a serial port. That may sound sarcastic, but it's not, since many manufacturers are ditching serial ports on computers. If you don't have a serial port then you would need to get something like a USB<->serial adapter or a serial port card that you plug into an expansion slot in your computer.

Assuming you've got that then you need to find the command set for the RF Power Supply, and write drivers for it so you can send the command to read the voltage, and then read the resposen. I would suggest looking in the Instrument Driver Network to see if a driver for your supply has already been written. 

[Dennis_Knutson]

To further clarify, you would only use a serial connection from the pc if the power supply also had a serial connection and if the remote programming commands of the power supply supported a query to read the output voltages. If you don't have both, then you would need some sort of device that measures dc voltages and the serial port of the pc would not apply.

[bassboss]

Just for a reference this is an RFX 600 Generator made by Advanced Energy. As you may know this product has a serial connection so there are no worries there. However, I was unable to find any sort of instrument drivers for this product. Are there any other routes I could take without an instrument driver?

[smercurio_fc]

Are you sure that's an actual serial (i.e., RS-232) interface? According to this post (made by a certain Knight who shall remain nameless ), that instrument doesn't have an RS-232 port.

[Coq_Rouge]

The "user port" on the instrument rear is not a RS232 port. So you must use a DAQ device.

[bassboss]

I'll try to reword my question a little better. I guess what I really want to find out is if I can read the dc voltage from the serial connection on the back of a computer. I already have all the wiring completed between the power supply and the serial connection on the computer so you can ignore that stuff. The serial port connection on the computer is a DB 9 pin. So I just need to figure out how to aquire the dc voltage entering the back of the computer through the serial port. I have taken a look at the Basic Serial Write and Read VI, but I am still a little lost. Since pin 2 is the receive data line I need to figure out how to read from that pin.

[Dennis_Knutson]

NO, NO, NO!

You seem to be ignoring what has been said. The RS-232 port on a pc is absolutely incapable of measuring a dc voltage. There is just no way to use the serial port for the Advanced Energy power supply. The connection on the power supply is not RS-232. They simply used a DB connector. Never confuse the physical connection type with some specific protocol. You will have to but some device that is capable of measuring voltages as there is nothing built into a pc with such a capability.

If you have actually connected the power supply to the RS-232 connector on the pc, there is a chance that you have damaged either the pc, the power supply, or both. If you have, it is because you have ignored all of the previous posts.