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FOCUS System Manual

Figure 5–2.

APM Loop during Normal Operation.

Example 1 - APM Loop during Normal

Operation

Figure 5-2 shows the synchronization directions

for an APM loop during normal operation. In this

example, the master clock source is not within this

loop. This means that all chassis in the loop are

programmed as slaves. Chassis 116 is synchro-

nized outside the loop.

Figure 5–3. APM Loop after Break

with “Disable Auto-sync into loop” Selected.

Example 2 - APM Loop after a Break with

“Disable Auto-sync into loop”

Selected

In this example (Figure 5-3), chassis 116 has

selected the "Disable Auto-sync into loop" field.

Thus, during a break, it remains synchronized out

of the loop. When a break occurs in the loop

between FOCUS chassis 612 and 136, chassis 612

becomes a master for the duration of the break.

With this configuration, the FOCUS chassis are

synchronizing to two different masters: 246 and

532 are synced to 612 and 136; 386 and 116 will

sync to a master outside of the loop. Here, you can

expect sync slips, primarily between chassis 116

and 532. Data mapped through these two chassis

will most likely have errors.

Figure 5–4. APM Loop after Break

with “Disable Auto-sync into loop” Not Selected.

Example 3 - APM Loop after a Break with

“Disable Auto-sync into loop”

Not Selected

In this example (Figure 5-4), chassis 116 has not

selected the "Disable Auto-sync into loop" field.

Thus, during a break, it switches its synchroniza-

tion into the loop. When a break occurs in the loop

between FOCUS chassis 612 and 136, chassis 612

becomes a master for the duration of the break.

With this configuration, all the FOCUS chassis in

the loop are synchronizing to a single master:

chassis 612. Because there are still two masters in

the FOCUS network, you can expect sync slips,

primarily between chassis 116 and the FOCUS

chassis outside this loop.

5.1.4.7 Defining Two APM Loops

When defining two APM loops for a FOCUS

chassis containing two dual transceivers, do not

assign loop definitions that form a “figure 8.” For

example, Figure 5-5 shows a sample FOCUS

network. In this network, the ONLY valid loop

definitions for chassis 526 are “X1-1 to X1-2”

FOCUS