Mediating between SNMP world and MODBUS TCP/IP


Thread Starter

Tim Mew

A number of devices (such as routers, transmission equipment, etc) are currently monitored (supervised) using SNMP (gets, traps). However, certain of these need to also be supervised by an existing Process Control System which uses MODBUS TCP/IP.

How do I do this?

Is there an off-the-self software product that on the one hand acts as an SNMP manager (ie polls devices using SNMP gets and receives SNMP traps), and then provides an MODBUS TCP/IP interface that allows the Process Control System to poll it using MODBUS TCP/IP?

Would it be hard to write such an application if an off-the-shelf software product is not available? Has anyone had experience in solving this problem?

Any help/advice would be much appreciated!

Many thanks!
You can use an SNMP OPC server from Phoenix Contact or Hirschmann (probably others as well) to get the SNMP info into an OPC server. From there you can use software such as iconics dataworx or similar to move data back and forth from a Modbus TCP/IP OPC server. There are several companies that offer all three of these software components that run on a pc.

Henry Suthon

I'm looking for the reverse of what you seek. I found something that may help me and might help you. The product seems to do Modbus to SNMP, but I am not sure it does SNMP to Modbus. Here is the company and website for your research.

Street address:
Control Solutions, Inc.
2179 Fourth Street, Suite 2-D
White Bear Lake, MN 55110
Voice: 651-426-4410 or 800-872-8613
Fax: 651-426-4418

Warm regards,

My company has developed an SNMP to Modbus gateway.
You are able to connect this gateway on your SNMP agent to acces the agent MIB using Modbus RTU or Modbus TCP protocol with the functions read or write n words.
The answer to your question, "can I use this converter?" is I don't know and doubt anyone else does, given the lack of information.

The presence of an RS-485 port is meaningless without knowing what protocol the port supports.

RS-485 is just a data highway that carries binary bits back and forth. RS-485 does not know or care what the bits mean, it just transports the bits.

A protocol is a set of rules for communicating; who talks, who listens, what the format of the data is, how to handle errors, sometimes how to establish or end communications.

Generally there's also an application program that knows what data it wants or needs, how to request the data, what to do with the data when it gets and how to present the data to a human being or another machine.

The device you showed only converts the protocol Modbus/TCP running over Ethernet to the protocol Modbus RTU running over RS-485. But it is just convering from one to the other. It has no idea what the bits mean or what to do with them.

What task are you trying to accomplish?
What is the application software that is going to accomplish whatever your task is?
What protocol or protocols does the software use to talk to the devices?
What hardware bus (data highway) does the application protocol use to talk to the devices? (Your device might be used here)