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Modbus Bridge and Its Role in Modbus Networks

modbus-bridge
The Modbus Bridge allows Modbus Networks to work on a myriad of network types.
This one allows for wireless connectivity
A Modbus bridge is a device that connects Modbus serial products to Modbus TCP Masters. It can be a critical piece of hardware in a Modbus network.

Modbus Bridge Allows Communication Between Modbus Serial and TCP Devices.

Modbus serial is the original variant of Modbus that travels over a serial connection. This serial connection commonly uses a RS-232 or RS-485 serial interface. Modbus TCP is an extra variant of the Modbus protocol. Internet users can access Modbus TCP at port 502, which is reserved for Modbus users on the TCP/IP stack.

Today, Modbus TCP has become an popular variant of the Modbus protocol. A Modbus bridge will allow users to transition to this variant, while still making use of their Modbus serial gear.

A Modbus bridge may be configured as a Slave or a Master bridge, simply by connecting to either device serially. A Modbus bridge can also be used for other Modbus variants, such as Modbus ASCII and Modbus RTU.

Connect 1000s of Slaves With a Single Modbus Bridge & Ethernet Card.

Devices joined to a Modbus bridge have single IP addresses, and addressing slaves through the Modbus bridge is now defined by the IP address and the slave address or unit id.

When a Modbus bridge receives a Modbus TCP request, it converts the messages into Modbus RTU or other variant of the Modbus protocol, creating a response using Modbus TCP. In these cases, the Modbus master most likely does not even see that it is not actually communicating with a Modbus TCP device.

Modbus Bridge Can Connect to Many Modbus TCP Masters at Once.

A Modbus bridge can connect to many Modbus TCP masters at one time. Serial slaves will actually see the Modbus bridge as the master device. The actual TCP Modbus masters will treat the Modbus bridge like a group of slaves, communicating as if each single master had sole access to the slave devices.


With more masters accessing the Modbus bridge, response times can become slightly sluggish. This is why one master device is recommended.

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