2. Programming Concepts
M relays M1200~M1254 are used to set the up/down counting direction for C200~C254
respectively. Setting the corresponding M relay ON will set the counter to count down.
Example:
LD X10
C200
Y0
X12
C200 K-5DCNT
X11
C200RST
X10
M1200
OUT M1200
LD X11
RST C200
LD X12
CNT C200 K-5
LD C200
OUT Y0
a) X10 drives M1200 to
determine counting direction
(up / down) of C200
b) When X11 goes from OFF to
ON, RST instsruction will be
executed and the PV (present
value) in C200 will be cleared
and contact C200 is OFF.
X10
X11
X12
01234543210-1-2-3-4-5-6-7 -8
0
-7-6-5-4-3
Contacts
Y0, C0
Accumulatively
increasing Accumulatively
increasing
Progressively
decreasing
PV in
C200
When the output contact
was On.
c) When X12 goes from Off to
On, PV of C200 will count up
(plus 1) or count down (minus
1).
d) When PV in C200 changes
from K-6 to K-5, the contact
C200 will be energized. When
PV in C200 changes from K-5
to K-6, the contact of C200
will be reset.
e) If MOV instruction is applied
through WPLSoft or HPP to
designate a value bigger than
SV to the PV register of C0,
next time when X1 goes from
OFF to ON, the contact C0
will be ON and PV of C0 will
equal SV.
2-33