How to choose the type of CAN to Modbus device
Senor of CAN interface
In the industrial field environment, we often need a variety of different types of equipment, such as the upper computer of the Modbus interface, the sensor of the CAN interface, etc. When we need to communicate between different types of devices, we often need the bus conversion module. For example, the communication between Modbus and CAN mentioned above, although our company has mature , the Modbus protocol needs to determine the master / slave relationship, but the CAN bus is not required. Therefore, we should choose the type of device according to the actual needs of the site to determine whether the buyer station or from the station before the purchase. How should we choose the correct CAN to Modbus conversion devices? Let's analyze it with a classic case.
Engineer Wang from Qinghai had a requirement like this: "My upper computer is the device of the standard CAN2.0 protocol without any other protocols. The lower computers are some sensors of Modbus RTU protocols. Now I want to use the upper computer to collect the information of the sensor. I think you have a CAN to Modbus RTU conversion device, can I use it directly? "
GCAN: “Hello, you need a CAN to Modbus master station device, our home is the CAN to Modbus slave station device, so your requirements couldn’t be achieve.”
So why do we think that the customer's needs are CAN to Modbus master station devices? We can go through the following steps.
First of all, we know that the customer's sensor is a Modbus slave device, and we need to use a Modbus master station as the upper computer to send the corresponding function code to read its data.
Second, we know that the client's upper computer is a CAN device, and the other end of the conversion module he needs is the CAN bus.
So, as shown above, what this customer needs is a CAN to Modbus RTU master device. So in what situation can we use our ? Here is a simple way to judge.
For this simple system in the last case, you can remember that when the upper computer has a Modbus protocol, such as some PLC, industrial control computers, and the like, reading data from the lower computer of the CAN protocol, you can use CAN to Modbus slave station. Otherwise, it cannot be used.
If it's a complex system, you can draw a flowchart, like above, and analyze it step by step from both ends to figure out exactly what you need.