Meggitt VM600 Hardware Manual

VM600 MPS hardware manual (standard version) MAMPS-HW/E 4 - 21
Edition 17 - February 2018
Alarm monitoring
MPC4 / IOC4T CARD PAIR
4.6.5 Danger Bypass function
NOTE: The safety version of the MPC4 card (MPC4SIL) does not does not support the
danger bypass (DB) function.
This function allows Danger relays to be inhibited, even when a Danger condition occurs. The
Danger information remains available to the MPS, but the Danger relays are de-activated to
prevent the monitored machine from being shut down.
The Danger conditions inhibited are the following individual alarms:
• The Danger+ and Danger generated by the four individual measurement channels.
• The Danger+ and Danger generated by the two dual measurement channels.
The outputs of any logic functions using these Danger conditions as inputs will be affected by
the use of the Danger Bypass function as the individual alarms are set to inactive for the
duration of a Danger Bypass.
The Danger Bypass function is activated when a low (0V) external signal is applied to the
Danger Bypass (DB) input on the IOC4T card.
See also 4.6.6 Channel inhibit function.
4.6.6 Channel inhibit function
NOTE: The safety version of the MPC4 card (MPC4SIL) does not does not support the
channel inhibit function.
The channel inhibit function allows individual MPC4 channels (measurement and speed) to
be temporarily bypassed, that is, it temporarily inhibits the protection offered by any
associated relays.
The channel inhibit function is intended to allow a component in a measurement system
front-end, such as a sensor/transducer or signal conditioner, to be replaced for an individual
channel while the other machinery monitoring channels and functions continue to operate as
normal.
This allows the machinery being monitored to continue to operate (if the protection offered by
the other machinery monitoring channels and functions is adequate). It also allows any
control system using the relays to avoid false trips during such maintenance activity.
When the channel inhibit function is activated for an MPC4 channel:
• The channel continues its processing as per its configuration but inhibits the protection
offered by any associated relays.
This allows the effect of any changes to the measurement system front-end to be
observed. In this way, it can also be ensured that there are no ongoing alarm conditions
before the de-activation of the channel inhibit.
• The sensor power supply output for the channel remains turned on, if enabled.
• Any DC output functionality associated with the channel continues, if enabled.
• The following flags (bits) for the channel processing are forced to a known state:
• For a measurement channel, the error bit (Err), OK system check (SOK), alarm (A+,
A) and danger (D+, D) flags are all forced to a normal state.
The sensor bypassed (SBP) flag and the invalid output flags are also set active (=1).
• For a speed channel, the error bit (Err), OK system check (SOK) and alarm (A+, A)
flags are all forced to a normal state.
The sensor bypassed (SBP) flag and the invalid output flags are also set active (=1).

Meggitt VM600 Specifications

General

Brand	Meggitt
Model	VM600
Category	Measuring Instruments
Language	English