"ModbusRTU slave" protocol not supported


JG_Utoronto

Recommended Posts

I am interested in configuring DAQFactory to be a Modbus slave, in order to have data collected by a separate logger (a Campbell Sci CR3000) using RS-232 serial connection. I understand I need to create a device using the ModbusRTU slave protocol, and assign Modbus register addresses to channels that I want to be able to access from the master.

I am currently using DAQFactory 5.83 Build 1632, and when I try to create a device with the ModbusRTU slave protocol (which appears under the protocol list), I get a message which states that the ModbusRTU slave protocol is not supprted by my version of DAQFactory.

Am I missing something? How can I get this protocol to work, or alternatively, perform the task I am trying to do in a different way without the ModbusRTU slave protocol.

Jeff

University of Toronto

Toronto, Canada

Link to comment
Share on other sites

5.83 is your release number, not the version you are using. Release's are numbered, 5.83, 5.84, etc. Versions are based on what product you purchased, Base, Pro, etc. Think of it like Windows. Win98, 2000, XP, Vista, 7 are all different releases. Media edition, Home, Pro, Ultimate are different versions with different features available. Releases change in time, versions typically just change features available.

For Modbus Slave support you need to have a version of DAQFactory that supports networking, say DF-Standard or DF-Pro.

If the Campbell device supports Modbus polling, this is going to be your best way to achieve this. Otherwise you are going to have to write your own custom listening protocol, which is pretty advanced.

Link to comment
Share on other sites

Modbus master is supported by all versions of DAQFactory except Express. "Master" means that DAQFactory is the master and the device the slave. The slave cannot initiate any conversations, so no, you cannot setup DAQFactory to be the Master and respond to requests from the device. That would be "Slave". These are Modbus definitions, not DAQFactory limitations. If the Campbell device can act as a slave, you could have DAQFactory periodically send values to the device, but I do not know the capabilities of this device.

Link to comment
Share on other sites

The ideal configuration for my application would be to have DAQFactory as the slave, so at least I'm good on one side. It sounds like the next step is to make sure the other device I'm using is okay as the master at that frequency.

Thanks for the quick help,

Jeff

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.