Input Operation
Some safety input modules, such as Bulletin 1732, 1734, and 1791, have safety inputs that can be configured as single or dual (Equivalent or Complement) point operation types. The selected type configures the safety module to view the inputs individually or as a pair:
- A single configuration is appropriate for single channel inputs or dual channel inputs that are monitored by a dual channel safety instruction like the Dual Channel Stop (DCS).
- A dual configuration configures dual channel discrepancy checking to take place at the module level. The channel data from the input module is sent to theGuardLogix®controller as either the safe state or energized state. For example, equivalent inputs are either both low (0) or both high (1).
Input Point Operation Types
IMPORTANT:
When inputs are configured for a dual point operation type and monitored by dual channel safety instructions, the instruction is unable to detect discrepancy faults.
The method of monitoring discrepancy has no impact on the safety rating. The main effect is the availability of diagnostic information:
- Module level diagnostics—Status indicators, input status bit, and application code can be written to message the I/O module to monitor 1 bit for a discrepancy fault.
- Dual channel instruction diagnostics—Fault codes include channel-specific discrepancy and whether the cause of a discrepancy is a delay or a change in state to a specific channel.
Some safety input modules, such as Bulletin 1756, 5069, and 5094, have no point operation type. All inputs are treated as single.
No Input Point Operation Types
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