Tag: modbus

Serial to Ethernet Converters: What to Know

3050 EGW1
This Square D PowerLogic 3050 Ethernet Gateway is a type of Serial to Ethernet Converter.

A Serial to Ethernet converter is typically used when you need to connect a device with a serial interface to a remote computer. These remote connections are common in industrial settings where constant, reliable connectivity is important.

Serial device servers can extend the lifespan of industrial control systems. Additionally, through the use of these systems legacy serial devices maintain their usefulness. Manufacturers can improve device management and data acquisition through the addition of Ethernet serial servers.

There are three types of Serial to Ethernet adapters. They are:

RS-232 to Ethernet, RS-422 to Ethernet, RS-485 to Ethernet Converter

Use devices like this to convert TCP/IP packets to serial data and back. They work in both directions. This allows serial devices like barcode scanners, sensors, or serial printers to communicate with a central (remote) computer. Conversely, it allows the computer to communicate with those serial devices. RS-232 to Ethernet uses software to identify itself as a virtual COM port to the computer.

57C414
The Automax 57414 is a Modbus Interface gateway.

Modbus TCP/IP gateways

Simply, a Modbus TCP/IP gateway is a Modbus RTU protocol running on Ethernet with a TCP interface. These devices use MODBUS messaging and TCP/IP protocols to connect PLCs, Input/Output modules, and gateways to simple field buses. Modbus data transactions are resistant to noise disruption.

Serial Bridge or Serial Tunnel connections

It’s also possible to use two device servers as a pair connection through an Ethernet TCP/IP network. Serial Bridge connections are protocol independent and don’t require routing configuration. Serial Bridge/Serial Tunnels will typically have Rx and Tx outputs. They may be powered over Ethernet or through a DC jack.

Mainframe computers, servers, or serial devices without Ethernet capability use Serial Bridge and Serial Tunnel connections. Configurations allow fixed-function controllers to be used in various ways (USB to SPI, USB to UART) without any user-developed firmware.

If you have questions about connectivity devices for your industrial location, reach out to our team today. We can help!

Modbus: An Introduction to the Protocol

When you’re running a modern factory, you have many machines that need to communicate with each other. These conversations occur over communication protocols that integrate with whatever native ‘language’ the machines speak. However, communications must translate each language to allow other networked devices to understand them. Modbus is one of the protocols that allow this communication to occur.

Modbus gateway I/O module from Reliance Electric.
Modbus Gateway I/O Module from Reliance Electric

What is Modbus?

This is the oldest and most popular of these communication protocols. Published by Modicon in 1979, it was originally used with the company’s programmable logic controllers or PLCs. But Modicon developed Modbus as an open protocol. Anyone could use them for free without licensing. Since its original development many software vendors, manufacturers, and other groups/organizations have supported the protocol.

The communication protocol uses serial lines to send data between devices. This is as simple as a single serial cable connected to serial ports on a Master device and a Slave device. Data moves at 9600 baud (bits per second) as series of zeroes and ones. Each zero or one is a single bit. Data follows regular patterns so 8 bits identifies as a larger byte.

Modbus is a type of SCADA (Supervisory Control and Data Acquisition) automation protocol. It is now owned by Schneider Electric. It is used to help devices and equipment communicate by providing a common language all can understand. This allows for different nodes on the network to interact with request/response type messages.

What Are Modbus Communication Protocol?

The original Modbus interface used serial RS-232 communication. However, as the technology developed, options expanded to include serial RS-485, serial RS-422, and Ethernet. Formatted Ethernet packets embed Modbus messages inside, creating versatile setups. Additionally, networks designed with mixed drops can run different protocols altogether. For example, a single network could run three drops, one using MB Ethernet TCP/IP, another MB RS-232, and a third MB RS-485.

Continue reading “Modbus: An Introduction to the Protocol”