46 Rockwell Automation Publication 1734-UM013N-EN-P - September 2017
Chapter 2 Safety Inputs, Safety Outputs and Safety Data
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 can 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 status is known as the combined safety input status or
combined safety output status.
Analog I/O Status Data
Individual input status indicates whether each analog input point is normal
(ON) or faulted (OFF). In addition, the following diagnostic data is monitored:
• User 24V Supply Overrange or Underrange
• Sensor Power Overcurrent or Undercurrent
• Channel Signal Overrange or Underrange
• Broken Wire Detected (4…20 mA current mode)
• Single-channel Discrepancy Error (channel fault)
In SIL 2 or SIL 3 operation, a single-channel discrepancy error occurs
when both measurements (internal to the module) of the same input signal
are not within tolerance. If a single-channel discrepancy occurs, indicating
a problem with the module, input status is set to zero and a zero input
value is reported for that channel.
• SIL 3 Dual-channel Discrepancy Error (channel fault)
• Alarms
– High High and Low Low Alarm Overrange or Underrange
– High and Low Alarms Overrange or Underrange
– Dual-channel Tachometer Dual Low Inputs Detected
– Tachometer Frequency Overrange or Underrange
The alarm status is reported in the Alarm Status attribute for each channel.
To Next Page
Loading...
Need help?
General
