Allen-Bradley 1756 Series

Rockwell Automation Publication 1756-UM013B-EN-P - October 2019 69
1756-OBV8S Output Module Features Chapter 4
Other Conditions That Can Trigger the Short Circuit
Diagnostic on the 1756-OBV8S Module
Tab le 20 describes conditions that can trigger the Short Circuit diagnostic.
When the conditions that trigger the diagnostics as described in Tab le 2 0
are
corrected, the results are the same as described in Table 19 on page 68
.
Table 20 - Conditions That Trigger Short Circuit Diagnostic
Conditions Output Behavior Tag and Diagnostic Combinations I/O Status Indicator State
• Output Mode - Sourcing
• Point Operation Type - Single
• Point Mode - Safety Pulse Test
• O.Ptxx.Data tag = 1
• Output point is shorted to 24V DC.
•Faults
•Turns off
• I.Ptxx.ShortCircuit tag = 1
• Short Circuit diagnostic = 1
• I.Ptxx.Fault tag = 1
or
• I.Ptxx.Fault tag = 1
• Internal Fault diagnostic = 1
IMPORTANT: The tag and diagnostic combinations that are
described occur on the faulted output point and all of its
associated group points.
The I/O status indicator for
the faulted output point
turns off.
These conditions exist on a pair of module outputs:
• Output Mode - Sourcing
• Point Operation Type - Dual
• Point Mode - Safety Pulse Test
• O.Ptxx.Data tag = 1 (Either output point in the pair)
• Output point is shorted to 24V DC (Either output
point in the pair).
•Faults
•Turns off
• I.Ptxx.ShortCircuit tag = 1
• I.Ptxx.Fault tag = 1
• Short Circuit diagnostic = 1
• Internal Fault diagnostic = 1
or
• I.Ptxx.Fault tag = 1
• Internal Fault diagnostic = 1
IMPORTANT: The tag and diagnostic combinations that are
described occur on the faulted output point and all of its
associated group points.
These conditions exist on a pair of module outputs:
• Output Mode - Sourcing
• Point Operation Type - Dual
• O.Ptxx.Data tag = 1 (Both output points in the pair)
• Output points are shorted to each other.
•Faults
•Turns off
• I.Ptxx.ShortCircuit tag = 1 (Both output points in the
pair)
• Short Circuit diagnostic = 1 (Both output points in the
pair)
• I.Ptxx.Fault tag = 1
or
• I.Ptxx.Fault tag = 1 (Faulted output point and all of its
associated group points)
• Internal Fault diagnostic = 1 (Faulted output point and all
of its associated group points