Muting device requirements – Banner DUO-TOUCH SG Two-Hand Control Safety Modules User Manual

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CAUTION: Do Not Use a Single Muting Device
A single device, such as one relay or one switch with two N.O. output contacts, may fail due to a
single fault. Such a fault could result in an unintentional mute cycle and cause an unsafe situation.

Muting Device Requirements

The muting devices (typically sensors or switches) must, at a minimum, com-
ply with the following requirements:

• A minimum of two independent hard-wired muting devices must be used.

If the sources disagree or conflict, the mute must end or must not occur.
No one source can initiate or continue a muted condition.

• The muting devices either must both have normally open contacts, or one

device have a PNP output and one device have an NPN output. These
contacts must “close” when the switch is actuated (to initiate a mute cy-
cle), and “open” when the switch is not actuated (to end a mute cycle)
and in a power off condition.

• The activation of the inputs to the muting module must be from separate

sources. These sources must be mounted separately in order to prevent
misadjustment or a single common mode failure resulting in an uninten-
ded muting condition. For example, this condition could cause physical
damage to the mounting surface, causing both muting devices to be
knocked out of alignment, resulting in false “muting” signals. Only one of
these sources may pass through, or be affected by, a programmable logic
controller or similar device.

• The devices must be installed so they can not be easily defeated or by-

passed.

• The devices must be mounted so their physical position and alignment

cannot change.

• It must not be possible for environmental conditions (such as extreme air-

borne contamination) to initiate a mute condition.

• The muting sensors or switches must not be set to use any delay or other

timing functions (unless accomplished in such a manner that does not
lessen the level of safety integrity of the system and does not create a
hazard by extending the mute cycle).

Figure 3.

If two pairs of mute sensors are required, parallel
the output (hard) contacts of M1 and M3, and M2
and M4, as shown above.

PNP

NPN

24V dc

0V dc

M11
M12
M21
M22

–

Figure 4.

If solid-state output mute devices are required, use
only devices with a discrete output, as shown
above. Two-wire sensors should not be used due
to the possibility of excessive leakage current
causing a false ON condition.

WARNING: Avoid Hazardous Installations
Two or four independent position switches (at M1–M2 or M3–M4) must be properly adjusted or
positioned 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. If improperly adjusted or positioned, injury or death
could result.
The user has the responsibility to satisfy all local, state, and national laws, rules, codes, and regulations
relating to the use of safety equipment in any particular application. It is extremely important to be sure
that all appropriate agency requirements have been met and that all installation and maintenance instruc-
tions contained in the appropriate manuals are followed.

DUO-TOUCH® SG Two-Hand Control Modules

P/N 109782 Rev.B