Figure 2: Single Network Break - Mircom FX-2200 Series Programming Manual

FX-2200 Programming Manual
Network Verify
Network Verify is an active process in which each panel and annunciator checks to make sure that
all other panels can communicate with it. This requires that ALL PANELS in the network have
same operating software and database.
Each panel sends out a Network Verify frame which is then passed around the network loop.
When the frame returns to its originating panel, it is checked to ensure it passed through the
correct number of panels. Also, each panel checks the Network Verify frames from other panels to
ensure that they are correct. Any errors and mismatches are identified.
Network Communications
Information is sent across the network in frames. In addition to the operator generated frames
described above, alarm, supervisory, and trouble frames are sent across the network
whenever a device or panel indicates a problem. There are two types of frames: specific and
broadcast. Specific frames are sent from one unit to another. Broadcast frames are sent from one
unit to all others.
Specific Frames
Specific frames deal with information generated at one panel and required at another. This type of
frame is passed from panel to panel until it reaches its destination. Each panel has a list as to
which port to send frames from to reach all other panels through the fewest number of panels.
Since networks generally have all communications links running at the same baud rate, this is
generally the shortest time as well.
If there is a break in the communications (see Figure 2), the panel that cannot pass the message
on sends it back the way it came. This causes the frame to go the long way around the network. If
there are two breaks in the network loop, the frame is again reversed at the second break. When
the originating panel receives it after the second turn around, the originating panel realizes there is
a major fault in the network and considers the frame to be orphaned and destroys it. This
generates a Network Reboot Required trouble. This is passed on to all other panels (or at least as
many as can be reached). The reason the orphan frame is destroyed is to prevent unexpected
operation when the network is finally repaired, such as a panel starts ringing its bells because of
an alarm from the previous day.

Figure 2: Single Network Break

Broadcast Frames
Broadcast frames deal with information that affects the entire network. When a broadcast frame is
created by a panel or annunciator, it is sent out both network communications ports. Each unit in
turn receives the broadcast in one port, act upon it and pass it on out the other port. Upon reaching
the unit that generated the broadcast frame, that unit then disposes of it. This means that under
normal circumstances, all units receive a broadcast twice and act upon it twice.
If there is break in a communications link (see Figure 2) the broadcast is disposed of by the unit
unable to pass it on. In the situation where a unit has been removed from the loop (see Figure 3),
the broadcast is passed only from com2 to com1 at the jump. In Figure 3, panel 5 passes the
3