CONTREX CX-1200 - Manual (Page 182)

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Series and Parallel Contacts - Operating on Bit Data
Often it is necessary to combine the state of more than one PLC bit (contact) to determine if another bit (coil)
should be energized. The series connection of two contacts represents the “ANDing” of the states; both
contacts need to be closed in order for energy to flow. The “AND” command is used to “AND” two PLC bits
(contacts) together. The following example shows how to program a simple series connected rung.
LOAD 55 MaxFbSpd
AND 24 Tmr1 Out
OUT 101 DO_1
MaxFbSpd
55
DO_1
101
Tmr1 Out
24
Similarly, the “OR” command is used to “OR” two PLC bits (contacts) together. This implements the ladder
logic of parallel connected contacts as the following example illustrates.
LOAD 55 MxFbSpd
OR 57 DrvNoRsp
OUT 101 DO_1
MxFbSpd
55
DO_1
101
DrvNoRsp
57
This can be expanded to include more bits.
LOAD 55 MaxFbSpd
OR 56 MaxAclDcl
OR 57 DrvNoRsp
OUT 101 DO_1
MaxFbSpd
55
DO_1
101
MaxAclDcl
56
DrvNoRsp
57