Rockwell Automation Publication 35-UM001A-EN-P - May 2022
129
Chapter 6 Safety Functions
Table 46 - Safety Input Specifications
Safety Input Alarms
The safety input logic can detect configuration, circuit, and discrepancy errors
for each safety input. When an error is detected, the associated safety input
data is put into the safe state, and the alarm type attribute is set.
Configuration Error
A configuration error occurs when a safety input’s configuration data is
invalid. If this error occurs, check to make sure that the configuration
attributes for the safety input are valid. A configuration error can also occur if
the safety input is selected for external pulse testing and the associated test
output’s configuration is not valid for this mode.
Circuit Error
A circuit error occurs in a safety input when a pulse test fails. There are two
types of circuit errors that can be reported:
•
Internal Circuit Error
•
External Circuit Error
An internal circuit error occurs when an internal pulse test fails. This means
that circuitry inside the module has failed. An internal circuit error may not be
recoverable; replacing the module may be required.
An external circuit error occurs when pulse testing by the safety input’s
associated test output fails. This error indicates the input circuitry external to
the card has failed.
Discrepancy and Dual Channel Errors
The discrepancy and dual channel errors are related, as a discrepancy can only
occur when the safety input is in dual channel mode. A discrepancy error
occurs when one of the dual channel safety inputs is not reporting the
expected safety input value. The safety input with the unexpected value reports
the discrepancy error. The other associated safety input will also be put in the
safe state and report a dual channel error alarm.
Table 45 - MSG Configuration for Safety Input Valid
Service Code
0x0E
Get attribute single
Class
0x3D
Safety Discrete Input Point Object
Instance
i
+ 1
Where
i
is the number of the safety input
Data Type
USINT
Attribute
0x64
100 (decimal)
Safety Input Valid
0
= Data invalid
1 = Data Valid
Input Type
Current Sinking
IEC 61131-2 (input type)
Type 3
Voltage, on-state
11…30V DC
Voltage, off-state
-3…5V DC
Current, on-state, minimum
2 mA
Current, off-state, maximum 1.5 mA
