Yaskawa 545 PLC - Manual (Page 10)

4 OPERATION
9 Function Number Method Specifics
4/12/94
Power up presents a special situation. There are two locations of nonvolatile
memory for the same parameter. The DSD memory is chosen on power up
over the PLC memory value. Value changes from the PLC after a power up
will not be accepted by the DSD/PLC interface until the PLC sends the value it
is reading from the DSD.
A sample ladder diagram for a TI PLC that meets the above requirements is
shown in Figure 1.
Figure 1. Sample Ladder Diagram for TI PLC
p = 1.0
A : V100
B : WY23
N = 2
A : WX41
B : WY33
N = 2
TIMR1
(C3)
C3
(C1)
C1
X1
C1
C1
(C2)
C2
MOVW1
MOVW2
X1 = (load PB) pick up to send new value set by PLC to DSD
V100 = new value as set by PLC
WY33 = PLC numeric output address (PLC to DSD)
WY41 = PLC numeric input address (DSD to PLC)
RD 3056-10