Circuit examples
189
1SVC 440 795 M0100
If the relay coils were activated, the logic relay transfers the
result to the contacts. M8 is now open again. No new pulse
can be formed until I1 has opened, since M7 is open for as
long as I1 is closed.
How does the value reach the shift register?
When shift pulse M8 = ON, the state of I2 (VALUE) is
transferred to storage location M1.
If I2 is activated, M1 is set. If I2 is deactivated, M1 is
deactivated via n/c contact I2.
How is the result shifted?
The logic relay activates the coils in accordance with the
rung and its result, from top to bottom. M4 assumes the
value of M3 (value 0 or 1) before M3 assumes the value of
M2. M3 assumes the value of M2, M2 the value of M1 and
M1 the value of I2.
Why are the values not constantly overwritten?
In this example, the coils are controlled only by the S and R
functions, i.e. the values are retained in on or off states even
though the coil is not constantly activated. The state of the
coil changes only if the rung up to the coil is activated. In this
circuit, the marker relay is therefore either set or reset. The
rungs of the coils (storage locations) are only activated via
M8 for one cycle. The result of activating the coils is stored
in the logic relay until a new pulse changes the state of the
coils.
How are all the storage locations cleared?
When I3 is activated, all the R coils of storage locations M1
to M4 are reset, i.e. the coils are deactivated. Since the reset
was entered at the end of the circuit diagram, the reset
function has priority over the set function.
How can the value of a storage location be
transferred?
Use the n/o or n/c contact of storage locations M1 to M4 and
wire them to an output relay or in the circuit diagram
according to the task required.
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