file transfer using modbus protocol

M

Thread Starter

michael scoutelis

I need to transfer files between a modbus client that is a Variable Messages System and a PC the modbus Master.

Anybody know about this Modbus protocol capability to incorporate in my system?

Thank you.
 
You can do this but depending upon the file size it can be extremelly slow. I work with energy meters that use modbus to transfer energy quality data. Even over Modbus TCPIP it can take 15 minutes+ to transfer a half meg. This can vary from device to device but the big limiting factor is the 125 registers a time for the max modbus package. I have some waveform files that can take an entire night to download.

The device must hold the 'file' and place the data in the registers. The device sets a register saying how many blocks of data need to be read. These registers are then read and, usually, a index register is written by the master telling the device to load the registers with the next data set. The process then repeats untill all the data sets are read.

If the device is ModbusTCPIP based its easier to use TFTP to retieve the file.
 
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