Allen-Bradley 1756 Series, User Manual, Page: 67 / 136

Rockwell Automation Publication 1756-UM013B-EN-P - October 2019 67
1756-OBV8S Output Module Features Chapter 4
No Load Detection
No Load Detection detects when a wire is disconnected from the output, or a
missing load for each output point in the Off state.
No Load Detection is enabled by default on the 1756-OBV8S modules. You
cannot configure it.
The module supports these minimum load currents:
• Safety output modules - The load detection current is ≥10 mA. For
example, 2.4 kΩ at 24V DC.
In the On state, the module must be connected to a load that draws a minimum
current equal to these values.
Table 16 describes what happens when a No Load
condition is detected
.
Table 17 describes what happens when a No Load
condition is corrected.
You can monitor a point for the presence of a No Load condition via the
diagnostics page that is available in the Module Properties dialog box in
Logix Designer application.
IMPORTANT An output must remain in the off state a minimum of 300 ms for an open load
to be detected.
Table 16 - No Load Detection - 1756-OBV8S Module
Condition I/O Status Indicator State
No Load condition exists • Flashing red if a No Load condition exists and the output is off.
• Flashing red/yellow if a No Load condition already exists and the output is
on.
IMPORTANT : A No Load condition is only detected when the output is off.
Table 17 - No Load Detection - 1756-OBV8S Module
Condition I/O Status Indicator State
No Load condition corrected • Off if the output is off.
• Steady yellow if the output is on.