Honeywell 301C Manuel De L'utilisateur page 72

Relay Priority
When computing the status of binary outputs such as relays, the 301C
prioritizes BACnet commands higher than internal gas events. This is
shown graphically below.
BACnet write priority 1 - Manual-Life Safety
BACnet write priority 2 - Automatic-Life Safety
BACnet write priority 3 -
BACnet write priority 4 -
BACnet write priority 5 - Critical Equipment Control
BACnet write priority 6 - Minimum On/Off
BACnet write priority 7 -
BACnet write priority 8 - Manual Operator
BACnet write priority 9 -
BACnet write priority 10 -
BACnet write priority 11 -
BACnet write priority 12 -
BACnet write priority 13 -
BACnet write priority 14 -
BACnet write priority 15 -
BACnet write priority 16 -
This can compromise the integrity of the gas detection system in cases
where erroneous or malicious BACnet traffic is present. In order to
mitigate this risk, version 19 and later BACnet software make some of
the relays immune to BACnet commands. This affects 301C relays 3
and 4 and 301R relays 5 to 8 on all 301R modules. Other relays and all
buzzers remain BACnet commandable. The E³Point relay remains
BACnet commandable.
Network designers are advised to use these BACnet-immune relays for
critical safety functions when malicious BACnet traffic is present. In
cases where an output must activate in response to either gas events
or a BACnet command, Honeywell recommends wiring the contacts of
two relays in parallel for a hardwired OR gate.
Internal 301C events
72