How to collect multiple sensor signals when RTU has only one RS485 interface

How to collect multiple sensor signals when there is only one RS485 interface on RTU data collector?

There is only one RS485 interface on the RTU data collector, but you can take the following methods when you need to collect multiple sensor signals:

First of all, since the RS485 interface is a standard interface, in RS485 communication network, it usually adopts the master-slave communication method, i.e., a host (in this case your RTU data collector) with multiple slaves (i.e., your multiple sensors). This type of communication allows one master to communicate with multiple slaves, thus enabling the acquisition of signals from multiple sensors.

Next, you need to make sure that each sensor supports the RS485 communication protocol and that their output signals can be transmitted over the RS485 interface.

There are two ways to merge multiple RS485 interfaces connected to one interface: serial connection and parallel connection.

1. Serial connection:

Connect multiple RS485 interfaces in series, i.e. connect the output of one interface to the input of the next interface. This allows the output signals of multiple interfaces to be transmitted serially to a single interface.

2. parallel connection:

Connect multiple RS485 interfaces in parallel, i.e. connect the outputs of multiple interfaces to the same bus. In this way, the output signals of multiple interfaces can be transmitted to one interface in parallel.

3. Configure the RTU device: set the appropriate communication parameters on the RTU data collector to ensure that it can communicate properly with each sensor. These parameters may include device address, function code, baud rate, data bits, stop bits, etc. You need to set them according to the specifications and requirements of the sensors.

Finally, by programming or configuring the software, you can set the RTU data collector to collect data from each sensor at predetermined intervals or trigger conditions and store it in the collector's internal memory or transmit it to a remote server for further processing and analysis.

Whether you are connecting in series or in parallel, you need to pay attention to the following points:

- Ensure that the electrical characteristics between the interfaces are matched, e.g. voltage and signal levels.

- Use suitable connection cables, such as twisted pair or coaxial cable, to minimise crosstalk and signal loss.

- The load capacity of the bus needs to be considered to ensure that the number of devices on the bus does not exceed the load capacity of the bus.

- If communication on the bus is required, appropriate communication protocols and address assignment methods need to be used.

In summary, the methods for combining multiple RS485 interfaces connected to a single interface are serial connection and parallel connection. Before implementing either of these methods, be sure to read and follow the user manuals for the RTUs and sensors to ensure that the devices are properly configured and connected. It may also be necessary to consider the electrical safety and environmental requirements of the system to ensure that the equipment is operating under the proper conditions.