Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 34)

34 Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Chapter 2 Understand the Operation of Safety Functions
Test Outputs Configured as
Muting Outputs When test outputs are used as muting outputs, typically for a muting lamp, a
circuit test is used to diagnose whether the circuit and lamp are operational. The
muting circuit test is run every 3 seconds, regardless of whether the circuit is logic
HI or LO. This could cause your muting output to flicker during normal
operation when it is logic LO.
The muting circuit test must fail twice in succession when the muting circuit is
logically HI, before a fault is declared. The results of the muting circuit test do
not affect the muting status when the circuit is logically LO.
A muting circuit fault will cause the muting status bit to go LO.
A muting circuit fault is declared 3…6 seconds after the fault occurs if the muting
circuit is logically HI for at least 6 seconds, because of the 3-second test interval
and that the muting circuit test must fail twice in successession. If the muting
circuit is logically HI for less than 6 seconds during a machine cycle, then the
asynchronous test and program scans could cause the fault detection to be
delayed for several machine cycles.
There is a difference in the operation of the muting status between some of the
DeviceNet safety I/O modules. This table shows the operation of the muting
status of all modules.
For catalog numbers 1791DS-IB16, 1791DS-IB8XOBV4, 1732DS-IB8, and
1732DS-IB8XOBV4, when using these GuardLogix safety application
instructions that monitor muting, should include the following codes to operate
properly when the muting status bit goes LO if the circuit is logically LO:
• DCSTM
• FSBM
• TSAM
• TSSM
Cat. No. Lamp Circuit Description
1791DS-IB16
(1)
(1) This module’s muting status bit goes LO when a fault occurs or when the circuit is logically LO.
HI Good Muting status HI/1
1791DS-IB8XOBV4
(1)
1732DS-IB8
(1)
1732DS-IB8XOBV4
(1)
Bad Muting status LO 1 second/HI 5 seconds (repeats)
LO status typically appears 3…6 seconds after fault
Muting status resets automatically
LO Good Muting status LO/0
Bad Muting status LO/0
1791DS-IB12 HI Good Muting status HI/1
1791DS-IB8XOB8
1791DS-IB4XOW4 Bad Muting status Lo 1 second/HI 5 seconds (repeats)
Muting status resets automatically
LO Good Muting status HI/1
Bad Muting status HI/1