Figure 8 - Analog Output Validation Block; Figure 9 - Digital Input Voting Block; Figure 10 - Digital Output Validation Block - Honeywell HC900 Safety Manual

Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
Digital Input Voting Function Block (DI-V)
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The common digital input function block is connected to any combination of three input channels. Up to
three input channels may be connected to the digital source; the function block output pin reflects the
majority of valid enabled input channels.
Digital Output Validation Function Block (DO-V)
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The digital input selected is compared to the DO channel output state for verification of output.
Note: The state used for DO-Vcomparison may require an inversion selection inside the function block
checked. Digital inputs "ON" state correspond to the presence of a "HIGH" input voltage on its terminals
whereas digital outputs "ON" either drive the output voltage "ON" for sourcing types and "OFF" for
sinking types of outputs.
Revision 1.9
01/14
Figure 8 – Analog Output Validation Block
Figure 9 – Digital Input Voting Block
Figure 10 – Digital Output Validation Block
HC900 Process & Safety Controller Safety Manual 43