Modbus is a communications protocol, which over the years has become a standard in the automation industry. The main reasons for the extensive use of Modbus over other communications
protocols are because it is:
1. Openly published and royalty-free
2. A relatively easy industrial network to deploy
3. Able to move raw bits or word data without placing many restrictions on vendors
Modbus is often used to connect a supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems. All IDEC MicroSmart Pentra PLCs support Modbus protocol. Using intuitive WindLDR software, you can configure the MicroSmart Pentra to be a Master or Slave device on a Modbus network. All MicroSmart Pentra PLCs support Modbus RTU/ASCII protocols and our CPU with embedded Ethernet port also supports Modbus TCP protocol.
Modbus RTU and ASCII
For standard MicroSmart Pentra PLCs, up to 7 communication ports can be configured as Modbus RTU and/or ASCII master or slave. It is even possible to have one PLC act as a master in one Modbus network, while at the same time acting as a slave in another Modbus network! There is no restriction on how the Modbus networks are set up with MicroSmart Pentra PLCs.
Modbus TCP
MicroSmart Pentra PLCs with embedded Ethernet port support Modbus TCP Client (Master) or Server (Slave) communications. When the MircroSmart Pentra is configured as a client (master) on the Modbus TCP network, up to 3 connections can be established. Each connection can communicate with up to 255 server (slave) devices. On top of that, you can make connections to the PLC using WindLDR software for program monitoring, upload or download. You can also use a web browser for remote access to the PLC, even though the Ethernet port is already configured for Modbus TCP connections.
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