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Sunday, December 16, 2018
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Modbus Connection to Bender Isometer
I am wondering if there is a way to connect a device to a PC via a virtual Modbus.

As I am knew to Modbus systems. I think I understand that a Modbus system has a Host device that calls for the data (my PC), a slave device the has the data (my Bender ISOMETER), and a go between that is connected to both via cables (the Modbus?). Correct me if I got any of this wrong.

My question is about if there is a way to connect the host and slave without that go between. I am using a Bender ISOMETER for the data collection and would like to not buy another device. Is there anything that anyone knows of that could connect the ISOMETER and my PC via a virtual Modbus? Or something similar that would bypass the second physical device?

I'm not sure if this is possible or not, but would be thankful for any insight you can give.

Modbus is a protocol, a set of rules for transferring real-time data from the slave to the master/client or what you call a host.

Modbus accomplishes data transfer when the Master sends a Function Code (FC) command to the Slave. The Function Code typically 'reads' some data from the slave by requesting the contents of specific data registers in the slave or by writes 'data to the slave by sending a data value which the slave puts in the slave's designated Modbus register.

VERY IMPORTANT
Modbus doesn't know what to do with data it fetches from a slave. That's not what a protocol does. The protocol transfers the data. It's up to some application software (that uses Modbus to get the data) to deal with the data once it's arrived.

There are provisions in the Modbus standard for Function Codes that read files of data, that is multiple data points, but the Function Codes that do so are not typically available with commercial software.

If your Isometer (whatever that is) does data collection, then Modbus is probably not the best protocol to use to get a file of collected data points out of the Isometer.

If you need real-time reporting of the isometric data, where the Master requests data every one second or 5 seconds or whatever is reasonable, the slave replies AND you have a software application that knows what to do with the data after Master fetches the data, then Modbus is a reasonably good tool to use for fetching real time data. But Modbus is never responsible for, nor does it know what to do with data beyond sticking into some temporary register.

Most vendors supply an application program (sometimes optionally at some cost) that is used to fetch data that is stored directly by a field device. Have you investigated such?