3. The activation of the inputs to the muting function must come from separate sources. These sources must be
mounted separately to prevent an unsafe muting condition resulting from misadjustment, misalignment, or a single
common mode failure, such as physical damage to the mounting surface. Only one of these sources may pass
through, or be affected by, a PLC or a similar device.
4. The muting devices must be installed so that they cannot be easily defeated or bypassed.
5. The muting devices must be mounted so that their physical position and alignment cannot be easily changed.
6. It must not be possible for environmental conditions, such as extreme airborne contamination, to initiate a mute
condition.
7. The muting devices must not be set to use any delay or other timing functions unless such functions are
accomplished so that no single component failure prevents the removal of the hazard, subsequent machine cycles
are prevented until the failure is corrected, and no hazard is created by extending the muted period.
6.2.3 Examples of Muting Sensors and Switches
Photoelectric Sensors (Opposed Mode)
Opposed-mode sensors, which initiate the muted condition when the beam path is blocked, should be configured for
dark operate (DO) and have open (non-conducting) output contacts in a power OFF condition. Both the emitter and
receiver from each pair should be powered from the same source, to eliminate common mode failures.
Photoelectric Sensors (Polarized Retroreflective Mode)
The user must ensure that false proxing (activation due to shiny or reflective surfaces) is not possible. Banner LP
sensors with linear polarization can greatly reduce or eliminate this effect.
Use a sensor configured for Light Operate (LO or N.O.) if initiating a mute when the retroreflective target or tape is
detected (for example, home position). Use a sensor configured for Dark Operate (DO or N.C.) when a blocked
beam path initiates the muted condition (for example, entry/exit). Both situations must have open (non-conducting)
output contacts in a power OFF condition.
Positive-Opening Safety Switches
Two (or four) independent switches, each with a minimum of one closed safety contact to initiate the mute cycle, are
typically used.
An application using a single switch with a single actuator and two closed contacts could result in an
unsafe situation.
Inductive Proximity Sensors
Typically, inductive proximity sensors are used to initiate a muted cycle when a metal surface is detected. Due to
excessive leakage current causing false ON conditions, two-wire sensors are not to be used. Only three- or four-wire
sensors that have discrete PNP or hard-contact outputs that are separate from the input power can be used.
Note:
Typical Entry/Exit is Dark Operate (DO) with through-beam or polarized retroreflective sensors.
Typical Home Position and Power Press applications are Light Operate (LO) or closed switch to mute.
WARNING:
•
Avoid hazardous installations
•
Improper adjustment or positioning could result in serious injury or death.
•
Properly adjust or position the two or four independent position switches so that they close only
after the hazard no longer exists and open again when the cycle is complete or the hazard is again
present.
•
The user is responsible for satisfying all local, state, and national laws, rules, codes, and
regulations relating to the use of safety equipment in any particular application. Ensure that all
appropriate agency requirements have been met and that all installation and maintenance
instructions contained in the appropriate manuals are followed.
6.2.4 Mute Enable (ME)
The Mute Enable function allows the user control of the state of a mute condition.
Select Mute Enable 1 or 2 for one of the input signals on the Input Configuration page of the configuration software.
•
To enable a mute condition, pull the Mute Enable 1 or 2 pin high (+24 V DC)
•
To disable a mute condition, connect the Mute Enable 1 or 2 pin to DC common (0 V DC) or leave it open
The +24 V DC and 0 V DC should come from the same power supply as the SX.
Typical uses for Mute Enable include:
1. Allowing the machine control logic to create a 'window' for muting to begin
SX Safety Laser Scanner
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