How can I control Sierra Instruments MFCs using LabVIEW without the needed drivers?

[s.garcia]

I'm trying to program these MFCs with labview and it would be much easier with the drivers. I have chekced NI's Driver Network and can't find anything. If someone knows how to program the controllers without the drivers, or even better if someone knows where I can find the drivers, it would be much appreciated. Thanks in advance.

[Dennis_Knutson]

What type of programming interface do they have? Is is serial, GPIB, Ethernet, etc? If you need to develop your own driver, that's the first step. Then, you would need programming information from the manual - what data to send to the instrument to control it, for example.

[s.garcia]

These controllers have RS485 communication interfaces. We are looking to control them through a MODBUS Network since we need to control six of them and a master/slave network would be pretty straightforward (in my opinion).

I was hoping to avoid writting my own driver since I've heard it can become very tedious. Any information is helpful. Thanks.

[Ben_S]

S.Garcia,

Hello! I did some poking around and wasn't able to find drivers for Sierra Instruments and MODBUS either. However, here are some documents on our website you might find helpful.

Introduction to MODBUS

Serial Communication Overview

Read Input Registers Using the Modbus Library for LabVIEW

Using Modbus I/O Servers 

[s.garcia]

Hey Ben:

What would you advise I should do to control these MFCs now that I know that the needed instrument drivers don't exist. Even though I have a good instructions LabVIEW book, I'm still a novice. What would you do?

I looked at the webpage links ou posted, but they don't really help regarding my problem with the drivers. Any suggestion is welcome. Thanks in advance.

-Sergio

[RavensFan]

You will need to start looking at the manuals that Sierra Instruments provide.  Especially if they have an advanced manual or a communications manual with details like Modbus commands and registers if it uses Modbus.  Or if it is a simpler RS-232/RS-485 interface, they might have their own proprietary communication protocol where you send a command and perhaps an ID# and wait to read back the response.

[s.garcia]

To my understanding, the purpose of the Modbus Networking was to communicate with the instruments in a master/slave protocol. This means that I would send a command to the instruments with an ID# and the instrument responds accordingly. Sierra Instruments does provide the specific commands needed to communicate with the MFCs, but my problem lies in that I don't really know how to get started as to writing the driver for the instrument. For example, I don't know where to insert the instrument commands provided in the VI (that's my main problem).

If there is an easier way to do this, please let me know. Thanks.

-Sergio

[Ben_S]

Sergio,

Ravens Fan beat me to it! (and is correct). You'll need to look at the manuals for your Sierra Instruments devices.

If your device is ModBus then you'll most likley be able to communicate with your Device by setting up a ModBus I/O server and reading/writing to it's registers.

If your device has serial communication abilities, then you'll be able to VISA commands in LabVIEW to send/recieve information to and from your device.

[Ben_S · Accepted solution]

 Sergio,

Check out these documents:

Developing LabVIEW Plug and Play Instrument Drivers
Development Tools and Resources

[s.garcia]

Ben:

Thanks for the link for the Instrument Drivers. I think this is going to work perfectly.

 -Sergio