CONTREX CX-1200 User Manual
Page 182
5 - 89
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