Modbus Server
Modbus Server is an innovative application providing advanced Modus/RTU over Ethernet TCP/IP to serial device connectivity.
The Modbus Server application was designed to provide enhanced connectivity for OPC servers and applications that require Modbus/RTU communication. While standard gateways provide connectivity for only one application per serial port, Modbus Server provides connectivity for up to six applications per serial port.
Modbus Server was designed to greatly enhance system maintenance capabilities. Included are comprehensive device and port specific diagnostic web pages that display status, message response timing, timeout and other error counts, and overall message statistics. A serial log is also included to provide message level diagnosis.
Modbus Server firmware supports the following controllers:
- Modbus/RTU masters over Ethernet TCP/IP (or COM port with a serial port redirector)
Modbus Server and firmware supports the following devices:
Modbus Server firmware is recommended in installations that require:
- Those installations that require only Modbus/RTU connectivity directly to a serial port and do not require the more advanced routing features found in Modbus Router.

Supported Interfaces:
- OPC Servers and Applications that require Modbus/RTU communication over Com ports or Ethernet TCP/IP connections
Modbus Server highlights:
- Supports Modbus/RTU over Ethernet TCP/IP connections to the corresponding serial port via intelligent Modbus message handling and routing.
- Supports only Modbus/RTU over Ethernet TCP/IP connections to a serial port. For Modbus/TCP functionality, please see Modbus Router and Modbus/TCP applications.
- Supports up to six Ethernet TCP/IP connections to each serial port.
- Supports up to 255 Modbus devices per port. Both valid, (1-247), and reserved, (248-255), device ids are supported
- Modbus/RTU specific message handling:
- CRC verification of all messages received on the TCP/IP and serial interfaces
- Timing out of responses from slave Modbus/RTU devices
- Broadcast message handling on connected port only
- System monitoring to ensure gateway operation:
- Gateway busy
- Application message timeouts
- Advanced diagnostics web pages:
- Modbus device specific statistics, response timing, and status. Up to 255 devices per serial port can be monitored simultaneously.
- Serial port specific statistics and status
- Serial port message logging
- Combined with a serial port redirector, such as the Comtrol Secure Port Redirector, can support up to six COM port connections to each serial port