Extension Article: Introduction to the Modbus Protocol
What do ARCNET, Ethernet and Modbus have in common? They were all developed in the 1970s and are still widely used today. Of course they have evolved over time, but their basic operation remains intact. Why change a good thing? There is one basic difference in the three technologies. Both ARCNET and Ethernet are data link and physical layer standards without a protocol while Modbus is a protocol that can operate over several data links and physical layers. Originally intended as a point-to-to interface between proprietary Modicon products, the protocol has found use in multi-drop and peer-to-peer networks like TCP/IP. It is no longer restricted to just Modicon equipment.
Extension Article: Introduction to Modbus Serial and Modbus TCP
In this article, we will discuss two implementations of the Modbus Protocol that were introduced in our previous article. The first implementation is the traditional implementation of Modbus over a serial line. The second implementation is more modern with Modbus operating over a TCP/IP network. Both implementations remain popular.
Essentials Article: Mapping of Modbus Registers to BACnet Objects
People have asked "what advantage does BACnet equipment have over Modbus equipment?" The simple answer is that BACnet equipment is discoverable while Modbus equipment is not. What this means is that BACnet devices are modeled as a collection of objects that are "network visible." By being able to view these BACnet objects and by understanding their pre-defined properties, much can be