EtherTRAK I/O modules (version 2.00 or later) support a flexible suite of communications options in support of your open systems:

Ethernet Port

The Ethernet port on EtherTRAK I/O modules will auto detect and respond to both SIXNET "I/O for Windows" and Open Modbus (Modbus/TCP) protocols. Messages from multiple computers can be received simultaneously in a mix of these two protocols. Up to two TCP/IP sessions and any number of UDP connections can exist at the same time.

RS485 Port

The RS485 port on an EtherTRAK module may serve as either a slave (receive I/O commands) or master (to repeat or "passthru" messages received over the Ethernet port). In either of these two modes, the RS485 port may be configured for SIXNET "I/O for Windows", Modbus RTU or Modbus ASCII protocol. (Please note that RS485 communications requires a single choice of mode and protocol, which is selected using the SIXNET I/O Tool Kit configuration software supplied with your EtherTRAK I/O.) A more detailed description of the two modes follows:

Passthru Mode

When a module receives a message over Ethernet, addressed to a station other than itself, it passes this message to the RS485 port for retransmission to other devices connected to this "passthru" port. If the port is configured for Modbus messaging, the Open Modbus (Ethernet) message will be translated into either Modbus ASCII or RTU protocol (as you have selected). The response from the slave RS485 device is retransmitted in the proper format over the Ethernet port to the originating master station. Please note that although RemoteTRAK I/O will respond to both Modbus and "I/O for Windows" messages, the use of the SIXNET "I/O for Windows" protocol will result in higher performance. Also, "I/O for Windows" communications will enable you to use many advanced SIXNET features, such as on-the-fly configuration changes, directly through the EtherTRAK I/O module.

Slave Mode

Slave mode is the default mode of an EtherTRAK module. This mode responds to commands from a master to update outputs or report inputs. The RS485 port on an EtherTRAK module, set in slave mode, enables the I/O module to accept commands from the RS485 port, Ethernet port, or both. In effect, the EtherTRAK module can serve as a RemoteTRAK I/O module. The user has a choice of "I/O for Windows", Modbus ASCII, or Modbus RTU protocols.

Selecting "I/O for Windows" or Modbus Protocol

Generally, "I/O for Windows" is the preferred protocol for SIXNET systems. In most cases it results in higher system performance and gives you the many benefits designed into SIXNET products, such as addressing I/O directly by tag name, and the many advantages provided by the Control Room Shared Resource Database in Windows-based systems. Systems using "I/O for Windows" communications can be configured on-line (while live) and can be addressed by multiple masters simultaneously.

Modbus is a single master protocol (although Ethernet can extend this capability in some situations). Modbus is recommended when the SIXNET I/O will share a communications channel with existing Modbus devices or when the software in your master station can only talk Modbus protocol. This is generally the case with non-Windows legacy systems and Windows software with limited suites of supported I/O drivers.