Specifications

7-1
SECTION VII
PRE-EMPTION AND TRANSIT PRIORITY PROGRAM/READ MODE
GENERAL
The LMD9200 provides a low and a high priority pre-
emption sequence for each of 6 pre-empt inputs on
MSD. There are also 6 pre-empt outputs which can be
controlled by the pre-emption sequences. To program
pre-emption:
PROGRAM READ, SELECTION 5, PRE-EMPTION
PROGRAMMING SEQUENCES....Selections 1-6...
Each sequence consists of up to 15 steps. The first
step of the sequence determines the entry phase(s) to
which the LMD will initially pre-empt to upon activation
of the input. The first step must be a phase, a
compatible dual ring phase pair such as 26, 37, etc.,
or All Red (code “90'').
For example, selecting sequence #1...
PG DWN to access instruction steps 4-6, 7-9, etc.
INSTRUCTION SET
After the first step, other phases can be specified, a
“special Interval or a code, where:
1-8 = Phases 1-8 allowed
.1-.9 = Special intervals
89 = Hold on input w/gap (see page 7-8)
9 0 = G o t o A l l R e d
9 1 = C V M O F F ( f l a s h )
9 2 = C V M O N
9 3 = E nable Peds during pre-empt
9 4 = I n h i b i t peds during pre-empt
9 5 = G o t o P r i o r i t y R e t u r n phases (see pg. 7-9)
9 6 = E nable coordination
9 7 = S t r i c t p e r m i s s i v e s enabled
9 8 = E x i t p r e - e m p t, no calls
9 9 = E x i t p r e - e m p t, ped calls all phases
T IME = 0-9.9 or 127 secs, timing of step
Acts as min time if HOI = ON
Acts as step time if HOI = OFF
The timer begins as soon as the phases specified by the
step are achieved. Use a minimum of .1 second timing for
all instructions except 91-99 which can all use 0. The
times below are special cases;
If Time =.0 for the first step, barrier phases in different
rings can clear independently (e.g. 2 & 6). Otherwise they
wait until both can clear, then clear together only. Repeat
the second step with same phases as the first using the
“real” hold time when using .0 for the first step.
If Time = 0 for 95 priority return instruction, it actually
times .2 secs
Time = gap time if 89 code used—see page 7-8
HOI = “Hold on Input” (On/Off). If On, the unit holds the
step after the timer times out until the input goes away. If
Off, it exits the step after timing out. When holding, the
step phases and conditions are maintained.
OUTPUTS = Pre-empt outputs activated during that step:
1-6 = PE 1-6 out
7 = Flash suffix (e.g. 17 = flash PE output 1)
Output note: If Time = 0 for the first step, any PE
outputs specified in the first step come on with the input,
even before pre-empt entry is initially achieved. The pre-
empt step entry phases would then be repeated in step 2
with the real entry phase hold time programmed.
General Operation
When an instruction step finishes timing, it proceeds to
the next step. If the current phases are not specified in the
next step or are not compatible with phases in that step,
they will immediately be forced off. Each step can consist
of a phase, a compatible phase pair, or any comb-ination
of non compatible phases 1-8. When non comp-atible
phases are specified, the unit will cycle between them.
One call Is placed on all step phases upon entry Into the
instruction. After that they are “on their own”.
When one a 91-97 type instruction is executed, the
phases (or All Red) specified from the last previous phase
instruction will remain in effect until a new instruction
including phases (or All Red) is executed.
Peds are normally inhibited into and during pre-emption.
Use code 93 to re-enable peds from that point forward—to
the end of pre-empt or until a 94 code.
The 96 and 97 codes pertain to coordination. Code 96 en-
ables coordination during preemption, typically used
during long pre-empts. Code 97 is usually executed just
prior to exit (the step before 98 or 99). This invokes strict
permissives upon exit from pre-emption so that only
phases allowed by the coordinator’s permissives will be
served. This helps to maintain coord after pre-empt.
--PRE-EMPTION DATA--
1-6. PROG SEQS 1-6 8. HI PE SET-UP
7.SPEC INT VALS .1-.9 9. LOW PRIOR PE
SEQ1|PHS-SPECL|TIME|HOI |PE-OUTS|90=RED
1 |16 | 25 | ON | 1 |99=RET
2 |99 | 0 |OFF | |.1-.9=
3 | | 0 |OFF | |SPEC’L