The specific way data is packaged and transmitted is known as a communication protocol. Fieldbus is a type of communication protocol that allows networking industrial devices, such as pressure transducers and level sensors to a PLC. Modbus is a popular fieldbus that allows a lot of data to be transferred, and supports two-way communication for remote operation (such as device programming and set-up).
There are two common types of Modbus: RTU and TCP/IP. Essentially, these are simply two different ways of transmitting data. While Modbus defines how the data is structured for transmission, RTU and TCP/IP wrap the structured data for specific methods of transmission.
Modbus RTU is a network of field devices using serial communication. Modbus sensors and devices can be daisy-chained in a network. RTU is extremely popular for industrial control networks as it has been around for a long time, and there is a lot of hardware and software that support it.
Modbus TCP/IP was developed to take advantage of the benefits of an Ethernet network. Our very own Kyle Yost, Design Engineer, explains:
“Modbus TCP/IP is basically the Modbus RTU protocol using the TCP interface in an Ethernet network. The Modbus data structure is defined using the application layer used in the TCP/IP protocol. The TCP, or transport protocol, is used to ensure data is received and sent correctly, and the IP is the address and routing information.”
”Essentially, the Modbus TCP/IP command is a Modbus RTU command included in an Ethernet TCP/IP wrapper. The benefit of using Modbus TCP/IP is using the existing Ethernet network equipment that is widely and available and cost effective.”
When it comes right down to it, these two protocols exist so that you can transmit data in a way that is cost effective and comfortable for you. Give us a call or drop our Measurement Experts an email to discuss your particular application, and we can help you determine how best to go about transmitting data.
