| 摘要 |
An I/O card 200 is used to interface two process controllers (28-36 figure 1 not shown) over a communication line 208, that is separate from a primary communication line 212 connecting the two process controllers to a workstation. The process controllers can access the I/O cards in a similar manner to I/O cards used to connect to field devices (40 and 42 figure 1 not shown). In this manner, the physical hardware and software architecture does not need to be modified for inter-controller communications. Inter-controller communications can be programmed as general I/O communication. The inter controller link may be via an intranet or the internet. The communication link may utilise Ethernet, Token ring, FDDI, ARCNET, WiFi, serial or parallel communication protocols. |
