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LabVIEW drivers - Carlo Gavazzi WM14 power analyzer and Modbus
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[programming topics] [drivers] [device simulators] [utilities] [projects] [events] [related topics] Carlo Gavazzi - WM14 power analyzerThe information provided by Carlo Gavazzi is a good starting point for creating a vi to control the WM14 power analyzer. The following text describes the requirements for controlling several power analyzers. Making the connectionThe WM14 can be connected to a PC trough a RS485 connection. Your PC should be equiped with a special add-on card or you should apply a RS232-to-RS485 converter. You can select either a 2 wire or a 4 wire connection. A proven connection is 2 wire with a 2 channel Advantech RS422/485 card. Establishing the right protocolThe protocol the WM14 uses, is a subset of the Modbus protocol. The settings for the serial connection are as follows:
Commands and responses are allways followed by an error check. A command consists of:
After sending the command the power analyzer will give the following responses:
The right addressSeveral power analyzers or modules can be connected to a single RS485 port when each module has been given an unique address. The modules can be given an address from 0 upto 255; the default address is 0. DownloadsLabVIEW library crc-16.vi modbus-clear.vi modbus-reading.vi wm14-ctvtarray.vi wm14-formatvaluestep1.vi wm14-formatvaluestep2.vi wm14-formatvaluestep3.vi wm14-rammemorymapping.vi wm14-reading.vi wm14-variablerepresentation.vi wm14-tester.vi Note: This library has been made with LabVIEW 6.1 Full Development System. It allows reading both 2 and 4 byte data. See alsoPower management application for methanol factory. Bart Boshuizen, 2006/04/05
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