7-15
Section
Timer and Counter Instructions
388
Flags
25407:
Step Start Flag; turns ON for one cycle when STEP(08) is executed and
can be used to reset counters in steps as shown below if necessary.
SNXT(09) 20000
CP
R
CNT 001
#0003
00000
00100
25407
STEP(08) 20000
1 cycle
25407
20000
Start
Address
Instruction
Operands
Address
Instruction
Operands
00000
LD
00000
00001
SNXT(09)
20000
00002
STEP(08)
20000
00003
LD
00100
00004
LD
25407
00005
CNT
01
#
0003
7-15 Timer and Counter Instructions
TIM and TIMH(15) are decrementing ON-delay timer instructions which require
a TC number and a set value (SV). STIM(69) is used to control the interval tim-
ers, which are used to activate interrupt routines.
CNT is a decrementing counter instruction and CNTR(12) is a reversible counter
instruction. Both require a TC number and a SV. Both are also connected to mul-
tiple instruction lines which serve as an input signal(s) and a reset. CTBL(63),
INT(89), and PRV(62) are used to manage the high-speed counter. INT(89) is
also used to stop pulse output.
Any one TC number cannot be defined twice, i.e., once it has been used as the
definer in any of the timer or counter instructions, it cannot be used again. Once
defined, TC numbers can be used as many times as required as operands in
instructions other than timer and counter instructions.
TC numbers run from 000 through 255 in the CPM2A/CPM2C PCs and from 000
through 127 in the CPM1/CPM1A/SRM1(-V2) PCs. No prefix is required when
using a TC number as a definer in a timer or counter instruction. Once defined as
a timer, a TC number can be prefixed with TIM for use as an operand in certain
instructions. The TIM prefix is used regardless of the timer instruction that was
used to define the timer. Once defined as a counter, a TC number can be pre-
fixed with CNT for use as an operand in certain instructions. The CNT is also
used regardless of the counter instruction that was used to define the counter.
TC numbers can be designated as operands that require either bit or word data.
When designated as an operand that requires bit data, the TC number accesses
a bit that functions as a ‘Completion Flag’ that indicates when the time/count has
expired, i.e., the bit, which is normally OFF, will turn ON when the designated SV
has expired. When designated as an operand that requires word data, the TC
number accesses a memory location that holds the present value (PV) of the
timer or counter. The PV of a timer or counter can thus be used as an operand in
CMP(20), or any other instruction for which the TC area is allowed. This is done
by designating the TC number used to define that timer or counter to access the
memory location that holds the PV.
