42 Rockwell Automation Publication 1734-UM013J-EN-P - July 2014
Chapter 2 Safety Inputs, Safety Outputs, and Safety Data
• If a muting lamp circuit is open when power is applied to the module, the
condition is detected when the test output is commanded on.
• When a lamp burns out and is replaced, the fault (muting status bit)
returns to the normal condition, independent of the state of the test
output.
I/O Status Data
In addition to I/O data, the module provides status data for monitoring the I/O
circuits. The status includes diagnostic data that can be read by the controllers
with 1 = ON/Normal and 0 = OFF/Fault/Alarm.
Digital I/O Status Data
The following data is monitored:
• Individual Point Input Status
• Combined Input Status
• Individual Point Output Status
• Combined Output Status
• Individual Test Output Status
• Individual Output Monitor (actual ON/OFF state of the outputs)
Individual Point status indicates whether each safety input, safety output, or test
output is normal (normal: ON, faulted: OFF). For fatal errors, communication
connections may be broken, so the status data cannot be read. Status bits are OFF
in the controller data table when the connection is lost.
Combined status is provided by an AND of the status of all safety inputs or all
safety outputs. When all inputs or outputs are normal, the respective combined
status is ON. When one or more of them has an error, the respective combined
status is OFF. This is known as the combined safety input status or combined
safety output status.
Table 4 - Muting Status Bit Operation
Test Output
Commanded
State
Lamp Condition Muting
Status
Bit
Description
ON Bad (open circuit) 0 Repair lamp.
ON Good 1 Normal condition. Lamp is operating properly.
OFF Bad (open circuit) 0 If lamp remains OFF after T1/T3 output cycled, repair lamp.
OFF Good 1 Normal condition.
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