Hi Michael, Modbus is a simple, open communication protocol originally created by Modicon/Schneider Electric. Though it has been widely used by others and considered "open" for several years, only last week did they give up their copyrights for it.
The Modbus protocol can be found here: http://www.modicon.com/techpubs/toc7.html Modbus-IDA now maintains it: www.modbus.org There are several options for communicating to Modbus devices from LabVIEW: 1. Write your own driver ------------------------- Modbus is a simple protocol so you can write a driver, or part of it that you need in LabVIEW. You'll use serial/VISA as with any other serial driver (note that there's a Modbus-TCP protocol as well). The protocol specification above should give you an idea of what's involved. In addition, C/C++ and VisualBasic APIs are also available. 2. Use existing LabVIEW VIs ---------------------------- There are several VIs available out there (none from NI though; some are from Alliance members). Some of these are free: http://www.air.nl/nlibrary/modbus_vi.html http://www.users.globalnet.co.uk/~pseudo/downloads.html (see Eurotherm; uses Modbus) http://www.softwarewithrelish.com/specs/BusVIEW.html http://www.ewebsite.nl/eng/html/modbus.html http://www.saphir.fr/SAPHIRnet/API/ModBusVIEW/index.htm http://labview.citeng.com/pagesEN/products/modbus.aspx Etc... 3. Use an OPC Server --------------------- As Modbus is heavily used in Industrial Automation, there are several OPC Servers available for it, including one from NI: http://ni.com/opc/opcservers.htm Here you'll find a free one from Matrikon: http://www.matrikon.com/drivers/FreeDownloads.asp In LabVIEW, as you very likely know, to talk to an OPC Server, you would either use DataSocket, or use the DSC module which has built-in support for OPC, and is recommended over DataSocket especially when you have a bunch of IO points. 4. Use an ActiveX Server ------------------------- There are ActiveX Servers available which talk Modbus. http://www.automatedsolutions.com/products/modbusrtu.asp A Google search returns a bunch for these. In your case, the turning of the motor, reading its speed, etc., really is writing and reading of the correct coils (discrete points), and registers. These will have "addresses" which the GS2 documentation should provide. Hope this gets you started. Regards, Khalid Ansari -------------------------------- "Ross, Michael" <[EMAIL PROTECTED]> wrote: Hello generous souls, I could really use a shortcut to running my new GS2 motor drive from Automation Direct. It has an RS232 interface and can be communicated with via MODBUS. The normal path to running these drives is via a PLC. Since I have a PC with a serial port, I wonder why I would care to use a PLC. I would like to command it directly with LV. I would like to do some very simple things like: turn the motor on verify that it is on or up to speed get the motor speed turn the motor off verify that the motor is off Unfortunately, MODBUS is one of those acronyms I have always read over quickly with out comprehending. Any advise or snippets will be appreciated. Michael E. Ross Senior Design Engineer Standard Motor Products, Inc. Engine Management 2717 Commerce Road Wilson, NC 27893 -------------------------------
