FX Series Programmable Controlers Applied Instructions 5
5-6
X22
P 10CJ
P10
e) A CJ instruction can be used to Jump forwards
throu
g
h a pro
g
ram, i.e. to-wards the END
instruction OR it can
j
ump backwards towards step
0. If a backwards
j
ump is used care must be taken
not to overrun the watchdo
g
timer settin
g
otherwise
the PLC will enter an error situation. For more
information on the watchdo
g
timer please see pa
g
e
5-12.
f) Unconditional
j
umps can be entered b
y
usin
g
special auxiliar
y
coils such as M8000. In this
situation while the PLC is in RUN the pro
g
ram will ALWAYS execute the CJ instruction in an
unconditional manner.
IMPORTANT:
• Timers and counters will freeze their current values if the
y
are skipped b
y
a CJ instruction.
For example if Y1 in the previous pro
g
ram (see point c) was replaced b
y
T0 K100 and the
CJ instruction was driven, the contents of T0 would not chan
g
e/increase until the CJ
instruction is no lon
g
er driven, i.e. the current timer value would freeze.
Hi
g
h speed counters are the onl
y
exception to this situation as the
y
are processed
independentl
y
of the main pro
g
ram.
Usin
g
applied instructions:
• Applied instructions are also skipped if the
y
are pro
g
rammed between the CJ instruction
and the destination pointer. However, The PLSY (FNC 57) and PWM (FNC 58) instructions
will operate continuousl
y
if the
y
were active before the CJ instruction was driven, otherwise
the
y
will be processed, i.e. skipped, as standard applied instructions.
Details of usin
g
CJ with other pro
g
ram flow instructions
• Further details can be found on pa
g
es 7-12 and 7-13 about the combined use of
different
pro
g
ram flow techniques (such as master control, MC etc).