The S100 I/O field wiring is connected to connection units, which are connected via standard cables to the S100 I/O boards. I/O boards can be exchanged while the system is running and new boards can be inserted live. A newly inserted board is taken into operation within 10 seconds. Local time tagging on input boards is available, providing a time resolution of 1ms. Dual boards and a special connection unit make a redundancy configuration, achieving a high degree of availability. The output in such configurations is supervised by the output signals through dedicated analog inputs on the board. Support for Intrinsic Safety isolators is available.
Application programs have access to process signals via so called data base (DB) elements. DB-elements also hold all I/O system configuration information. Configuring the I/O system involves filling in DB elements with parameters for each module and channel. Typical parameters are tag name, signal range, filter time, etc. Analog values are automatically converted to process-related engineering units, relieving the application programmer from all considerations about scaling.
Analog and binary input modules in S100 I/O are scanned cyclically, the cycle being possible to synchronize with the application program (PC) execution. For binary input modules interrupt-controlled updating of the DB element can be optionally selected. Outputs are the updated immediately after the PC execution has finished, if value has been changed. For regulatory control this means that within one scan cycle, analog input is read, the control algorithm executed and the resulting output is presented on the output terminals.