Applies To:
  • CitectSCADA 3.00 4.00

An overview of the Omron family of PLCs. 

Omron PLCs may be networked together using SYSMAC-WAY, SYSMAC-LINK, SYSMAC-NET and FINS. The differences between these are described below:

(1) SYSMAC-WAY, also known as host link, is the name given to serial communications used with Omron PLCs. The serial line can be copper or optic fibre, supporting up to 32 PLCs. Multi dropping of RS232 is not recommended due to electrical limitations. The SYSMAC-WAY network is supported by the Citect OMRON driver, and the protocol is the same whether used with RS232, RS422 or optic fibre.

(2) SYSMAC-LINK supports high speed communications using optic fibre or coaxial cable. A special Sysmac Link board is required in the computer, along with MS-DOS drivers. This network supports up to 62 nodes (PLCs) which may include a single computer. This network also allows a data link between the PLCs, which allows them to communicate transparently to the computer.

(3) SYSMAC-NET supports high speed communications using optic fibre. The network is configured in a loop so that a break in a cable does not cause the entire network to break. Instead the system will automatically loop back so as to continue communications. Bridges may be used to join several loops into a larger network. Also, power may be supplied to the comms card in the PLC so if the comms card fails the node will still remain active.

(4) FINS is an ethernet based protocol which applies to the CV series of PLCs only. Each node in the network is set to a separate TCP/IP address. This protocol is supported by the Citect OMFINS driver.

Note that a subset of the FINS commands may be used with a SYSMAC-LINK and a SYSMAC-NET network. This latter configuration is not shown here.