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Inputs
Safety inputs to a Safety System will be either De-energize to trip inputs or analog inputs.

Digital inputs
De-energize to trip inputs (usually termed fail-safe) will be used for all safety digital inputs. The number of safety monitoring signals required for each safety parameter will depend primarily on the safety integrity level (safety classification) required to be achieved, the 100% proof test cycle required and the level of diagnostics available from the field device.
All safety digital inputs will be wired to a Digital Input Termination Card. Where the safety integrity level requires that more than one field sensor monitoring a safety parameter, each of these sensors should be, where practical, wired to separate Termination Cards. The Simplex part of the termination card (for example, fuses) must be considered for reliability analysis as part of the field loop.

The Termination Card will be connected to the Triguard SC300E Input Module via a standard system cable that connects to the socket on the appropriate Hot Repair Adapter Card or chassis slot.
Through the hot repair adapter card, where required, and the chassis backplane connector the input signal is connected to the configured digital input slot position where a Digital Input Module would be located.
All the chassis slots and, where required, its hot repair partner slots configured for the Digital Input Module must also have the polarization keys fitted and configured for this type of module as specified in the Module and Chassis Users Manuals.
Where the safety integrity level requires that separate sensors are used to monitor the same safety parameters they should be configured to separate Digital Input Modules where practical.

Analog inputs
Analog transmitters are used to monitor safety parameters and inherently provide an increased level of diagnostics with respect to a simple fail-safe digital input. Analog signals always provide values within a set operating range. For safety-related transmitters this should be 4-20 mA or 1-5 volts allowing for fault indication below say 3 mA (0.75 V) and 20 mA (5 V). If overrange detection is required, a 0-10 V input module must be used. All monitored faults from the analog signals must be used by the application software to produce fail-safe results (for example, failed transmitter demands a shutdown).
The number of analog transmitters used to monitor a safety parameter will be dependent on the system integrity level (safety classification) requirement of the loop, the 100% proof test cycle of the loop and the level of diagnostics available from the transmitter.
The field analog signal is wired to the Analog Input Termination Card. Where the safety integrity levels require that more than one transmitter is used to monitor a safety parameter, then the additional analog input signals should be wired to separate Termination Cards where practical. The Simplex circuitry on the termination card must be considered for reliability as part of the transmitter loop (for example, fuses and monitoring resistors where fitted). Refer to Figure B-1.
The signal is connected from the termination card to the Triguard SC300E input module via a standard system cable, which connects to the socket on the appropriate Hot Repair Adapter Card or chassis connector.