Changing a driver form serial to USB

[Sbotzer]

Hello,

I've downloaded a driver for a mass flow controler and the interface is serial. I have a usb connection so i would like to know if there is a way to change this?

Shay

[Pnt]

The easiest way is to use a USB to Serial adapter

[Dennis_Knutson]

The answer really depends on the type of USB connection you have. If it emulates a serial port, then you don't have to do a thing. If it is a USBTMC instrument, you might not need to do much either. Find out from the vendor the type of USB protocol that is implemented.

[mikeporter]

Yes, a number of people make serial interfaces that plug into a USB port. I have seen devices that provide as many as 8 added serial ports. When you plug them in  Windows recognizes them and assigns them the next port number(s) in order. For example, your PC probably has COM 1 and 2 ports builtin. Inserting a single-port adapter would cause Windows to make the adapter port 3, a 4-port adapter would be assigned ports 3 through 6, and so on.

Once Windows assigns them a port number you talk to them from LV the same as you would any other serial port.

Mike...

[Sbotzer]

Hey Mike,

Just to be sure I understand what u r saying, I should get a cable that converts from USB to serial and than it would work?

I want to explain you my problem.

We have an Alicat Flow Mass controller. Both Alicat and NI have drivers for this FMC in thier website but with a serial interface. 

Our FMC connects to an NI DAX-9172 which is connected with a USB to the computer. The NI DAX-9172 has several slots and we have other things connected to it besides the FMC (like thermocouple and a few 4-20mA inputs). You say that we can just switch the cable from USB to serial with a convertor and everything would work ok?

Thanks in advance

Shay

[mikeporter]

I'm confused... How do you have the FMC connected to the 9172? The later is a usb interface DAQ chassis. You have described the former as a serial interface device. Are there analog control inputs on the FMC or something?

But if you need a serial port to control the FMC the usb to serial converter will do the job.

Mike...

[Sbotzer]

The FMC has an 8 pin cable output and I connected the 8 pin cable to the 9172 through the 9203 AI 4-20mA inputs. Our 9172 has several 9203 inputs and a few outputs.

So i just need to convert the 9172 output from a usb to a serial?

Thanks very much

Shay

[Dennis_Knutson]

That's not making any sense at all. You were asking about connecting a mass flow controller and now you are talking about connecting the DAQ chassis. You don't change a thing with the NI DAQ chassis. You connect it's USB port to a USB port on the pc. If the mass flow controller has a USB port, you connect that to a USB port on the pc. If the mass flow controller has an RS-232 port, you connect that to an RS-232 port on the pc.

[Sbotzer]

It didn't make sense to me also. But now i understand that i can't just change from usb to serial as many have suggested because i didn't explain myself right.

So let's try this again:

My FMC has an 8 pin cable coming out of it. i connected the 8 pins to the NI DAQ chassis. When I run labview i get two signals (4-20mA) from it as there are two sensors in the FMC (pressure and tempreture). The DAQ chassis is connected to my pc with a usb.

Now, NI and Alicat (the FMC company) both have drivers for this product and i would be happy to use them instead of writing them again. The drivers are with a serial interface and when i try to run them i get errors.

I was wondering if there is something i can do that can manipulate the drivers or the hardware so i won't have to write the from the start.

Thanks again for the help

Shay

[Dennis_Knutson]

It sounds like the driver is to be used when the mass flow controller is connected directly to the pc so that you can read the pressure and temperature. You have connected the controller to the DAQ instead so you will have to convert the signals to pressure and temperature readings. There is no way to use the serial driver. Does this model of controller not have a serial port? Is that why you have it connected to the DAQ chassis?