Mute Lamp Output (ML)
Depending on a risk assessment and relevant standards, some applications require that a lamp (or other means) be used to
indicate when the safety device, such as a light screen, is muted. The Safety Controller provides a signal that the protective
function is suspended through the Mute status output.
Important: Mute Status Indication
Indication that the safety device is muted must be provided and be readily observable from the location
of the muted safety device. Operation of the indicator may need to be verified by the operator at suitable
intervals.
Muting Time Limit
The muting time limit allows the user to select a maximum period of time that muting is allowed to occur. This feature
hinders the intentional defeat of the muting devices to initiate an inappropriate mute. It is also useful for detecting a
common mode failure that would affect all mute devices in the application. The time limit can be adjusted from 1 second to
30 minutes, in increments of 100 milliseconds (the default is 30 s). The mute time limit may also be set to Infinite (disabled).
The timer begins when the second muting device meets the simultaneity requirement (within 3 seconds of the first device).
After the timer expires, the mute ends despite what the signals from the mute devices indicate. If the input device being
muted is in an Off state, the corresponding Muting Block output turns off.
WARNING: Muting Time Limit. Select an infinite time for the Muting Time Limit only if the possibility of an
inappropriate or unintended mute cycle is minimized, as determined, and allowed by the machine’s risk
assessment. The user is responsible to make sure that this does not create a hazardous situation.
Mute Off-Delay Time
A delay time may be established to extend the Mute state up to the selected time (1, 2, 3, 4, or 5 seconds) after the Mute
Sensor Pair is no longer signaling a muted condition. Off-delay is typically used for Safety Light Screen/Grid workcell "Exit
Only" applications with mute sensors located only on one side of the defined area. The Muting Block output will remain On
for up to 5 seconds after the first mute device is cleared, or until the muted Safety Input device (Mute Block In) returns to a
Run state, whichever comes first.
Mute on Power-Up
This function initiates a mute cycle after power is applied to the Safety Controller. If selected, the Mute on Power-Up
function initiates a mute when:
• The Mute Enable input is On (if configured)
• The safety device inputs are active (in Run mode)
• Mute sensors M1-M2 (or M3-M4, if used, but not all four) are closed
If Auto Power-Up is configured, the Safety Controller allows approximately 2 seconds for the input devices to become
active to accommodate systems that may not be immediately active at power-up.
If Manual Power-Up is configured and all other conditions are satisfied, the first valid Power-Up Reset after the muted
safety inputs are active (Run state or closed) will result in a mute cycle. The Mute On Power-up function should be used
only if safety can be assured when the mute cycle is expected, and the use of this function is the result of a risk assessment
and is required by that particular machine operation.
WARNING: The Mute on Power-Up should be used only in applications where:
• Muting the System (MP1 and MP2 closed) when power is applied is required
• Using it does not, in any situation, expose personnel to hazard
Mute Sensor Pair Debounce Times
The input debounce times, accessible under the Advanced settings in the Mute Sensor Pair properties window, may be
used to extend a mute cycle after a mute sensor signal is removed. By configuring the close-to-open debounce time, the
mute cycle may be extended up to 1.5 seconds (1500 ms) to allow the Safety Input Device to turn On. The start of the mute
cycle can also be delayed by configuring the open-to-close debounce time.
Muting Function Requirements
The beginning and the end of a mute cycle is triggered by signals from a pair of muting devices. The muting device circuit
options are configurable and shown in the Mute Sensor Pair Properties window. A proper mute signal occurs when both
channels of the mute device change to the Mute Active states while the muted safeguard is in the Run state.
XS/SC26-2 and SC10-2 Safety Controllers
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