CODEWITHSUNDEEP
ruby-on-railstcpcloudmodbus
ageorgie
ageorgie

Reputation: 65

Need to communicate with a box using Modbus over TCP/IP from my cloud-based server

So I don't have much experience with Modbus but my problem is essentially what's in the title. Would I need a controller that talks to the box and then reformat the message and pushes it to the server? Or can the server talk to the box directly? BTW, my cloud app uses Rails if that helps. I'm not sure what other information is required so feel free to let me know.

Thanks.

Upvotes: 2

Views: 1131

Answers (2)

avra
avra

Reputation: 3730

All you need is a MODBUS library for Ruby.

Upvotes: 1

Greg Philpott
Greg Philpott

Reputation: 54

Modbus originated as a serial master/slave protocol with two different modes; 'ASCII' and 'RTU'. The different modes have different packet formats (one uses ASCII characters, and the other uses binary), different rules for detecting the start and end of packets, and different error detection (checksum or CRC). Modbus over TCP/IP basically takes the 'RTU' packet, discards the CRC, adds some extra addressing, and wraps it up in a TCP packet. Provided you are happy to implement the code to construct (and interpret) packets in your cloud app then there's no reason why the server cannot talk to the box directly.

One thing you should bear in mind is that a 'Modbus client' issues commands to a 'Modbus server', which then responds. So you need to work out whether your box is a 'Modbus client' or 'Modbus server'.

The only thing I'm not sure about is IP addresses. If your cloud-based server gets a different IP address each time it runs then that might be a problem if it is acting as the 'Modbus server', or if your box has an access control mechanism.

All the documentation can be downloaded from www.modbus.org

Upvotes: 0

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