instrument drivers for mecmesin and gaeltec instruments

[Tim C]

Hi,

Im fairly new to labview, im attempting to use 8.2, and daq devices so appologies if some of these questions appear idiotic.
I need to acquire data from a mecmesin BFG 50N force gauge and a Gaeltec pressure catheter. Neither of these devices have NI drivers. I want to use these with a laptop, the two devices used rs232 connections, but to interface them with the laptop i am using USB serial converters.

I am unclear as to whether i should use the create instrument driver project wizard or whether i should use visa to create the driver i need. (I have looked at the tutorials on both and i am still confused).
I am also unclear as to whether the devices are USBTMC or USB RAW or if they are neither considering that they were not originally usb devices. How would i go about determining this?

I am not especially familiar with how rs232 works but I have access to a NI DAQ device (6251 M series). Would it be possible to aquire the data by hardwiring the correct pins from the rs232 connector into this? If so what do i need to do?

Thanks for reading, and appologies for being a complete labview dunce!

[Albert.Geven]

Hi

The best you can do is to use VISA to get the rs232 communications going.
Init the serial port
Writing a string a command
reading a string, followed by interpreting it.

But start with the basic serial example look in help/find examples/hardware input output/serial/ basic serial write and read

[Dennis_Knutson]

To just add a few more details, your instruments are nmot USBTMC or any other USB. They are just plain serial devices. It does not matter that they are connected to USB-RS232 converters.

Using a DAQ card is not practical at all and in most cases, is impossible.

Before you start writing any code, I would strongly recomend that you do some basic tests of the communication with a program like Hyperterminal. There are just too many things that can go wrong without having a new program added to the mix. You will have enough challenges getting the correct cable, com parameters, and commands to work. Also, if you have problems, the vendor will almost certainly have experience with Hyperterminal. Many will never have heard of LabVIEW.

[Albert.Geven]

HI Dennis

Maybe it is time that somebody finds or writes a LabVIEW implementation of hyperterminal

One of the most forgotten things in the basic serial write and read is the addition of CR/LF
or better formulated the "End Of Line" definition.

[Dennis_Knutson]

Albert,

You're probably right. In my programs, I seldom have a need or even want, any type of GUI but it would makes things convenient at times.

[Tim C]

Thank you both for your comments,

I have never used hyperterminal, but it seems like a pretty easy to use program.

What exactly do i need to test for with hyperterminal and is there any resource that will give me ideas on how to do this?

Should i try to communicate with the devices with the serial/usb convertors attached or should i first try to use only the serial ports?

This could be problematic as both pcs i am using do not have rs232 connections.

[Dennis_Knutson]

It really does no good to do anything with the instruments connected. Either a built-in port or a USB-RS232 converter.

Before you connect though, you need to open the manual and see what type of serial cable is required. There are tow basic types, straight-through or null modem. A null modem cable may sometimes be called a cross-over type. After connection, you then need to configure the baud rate, parity, stop bits according to what the manual says the instrument uses. Once you've done that, then you can start trying the commands that the manual lists.

[Tim C]

The comms settings for the BFG are fixed to 9600 baud, 8 data bits, parity - none, stop - 1, and flow control set None. I dont know what type the rs232 cable is.

I am using this along with a Mitutoyo height scale and these are then connected to the pc via a "digicon x" connector, a rs232 cable and a serial to usb to serial connector.

this is shown here

http://www.mecmesin.com/ucm/admin/upload/documents/56dpt_b.pdf

I think the comms settings are the same for the height scale because both the height scale and the force gague are used with mecmesin software installed on the pc and there is only one comms settings option in the software.

How should i proceed?

The Pressure device actually has an analogue pressure sensor. it is connected to a digital recorder which is in turn connected to the pc via rs232. If i could find out from the manufacturer what the input and output parameters are for the analogue sensor are i think it would be much easier to aquire data straight from the sensor using a daq device and forget about using the recorder. Would you agree?

The recorder is a shoddy enough piece of kit anyway, its battery powered and can only sample at 8Hz, It would be no loss to me if i got rid of it.