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MM-TA-12B Muting Module
Instruction Manual
WARNING . . .
Muting Limitations
Muting is allowed only
during the non-hazardous portion
of the machine cycle.
A muting application must be
designed so that no single compo-
nent failure can prevent the stop
command or allow subsequent
machine cycles until the failure is
corrected (per OSHA
1910.217(c)(3)(iii)(d), ANSI B11.19
section 4.2.3.3.7).
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1.10 External Device Monitoring (EDM)
Two inputs are provided (see Figure 1.1) for monitoring the state of external
devices, such as MPCEs. These terminals are labeled "EDM1" and "EDM2" at the
Machine Interface connection. The Module's EDM inputs can be configured in
three ways: one-channel, two-channel, or no monitoring (see Figure 3-2 for DIP
switch settings and Section 3.7.2 for external hookup). One- and two-channel
EDM is used when the OSSD outputs directly control the de-energizing of the
MPCEs or external devices.
• One-Channel Monitoring: a series connection of closed monitor contacts that
are forced-guided (or captive contact) from each device controlled by the
Muting Module. The monitor contacts should open within 200 milliseconds of
the OSSD outputs going ON (a GO condition) and should close within 200 mil-
liseconds of the OSSD outputs going OFF and remain closed (a STOP condi-
tion), or a lockout will occur (see Diagnostic Display, Section 5.2).
• Two-Channel Monitoring: an independent connection of closed monitor con-
tacts that are forced-guided (or captive contact) from each device controlled by
the Muting Module. While the OSSDs are ON, the inputs may change state
(either both open, or both closed). If the inputs remain in opposite states for
more than 200 milliseconds, a lockout will occur. Additionally, both inputs must
be closed 200 ms after the OSSD outputs go OFF or a lockout will occur (see
Diagnostic Display, Section 5.2).
• No Monitoring: uses the "EDM Disable" configuration with inputs EDM1 and
EDM2 left open (not connected). If the Module is set for No Monitoring, the
user must ensure that any single failure of the external devices does not result
in a hazardous condition and a successive machine cycle will be prevented (see
Section 1.5, Control Reliability).
1.11 Mute Devices and Mute Inputs (M1 – M4)
Application of the Muting Function
To mute the primary safeguard appropriately, the design of a muting system
must:
1) Identify the non-hazardous portion of the machine cycle,
2) Involve the selection of the proper muting devices, and
3) Include proper mounting and installation of those devices.
The Module can monitor and respond to redundant signals that initiate the mute.
The mute then suspends the safeguarding function by ignoring the state of the
MSSI; this allows an object or person to pass through the defined area without
generating a stop command. (This should not be confused with blanking, which
disables one or more beams in a safety light screen, resulting in larger minimum
object sensitivity.) See Appendix A for example mute timing sequences.
The mute may be triggered by a variety of external devices. This feature provides
a variety of options (see Sections 3.5.2 - 3.5.3) to tailor the System to the
requirements of a specific application.
A pair of muting devices must be triggered simultaneously (within 3 seconds of
one another). This reduces the chance of common mode failures or defeat.
Introduction
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