Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 122)

Publication 1760-UM001D-EN-P - September 2005
4-62 Draw a Circuit Diagram with Pico
If the relay coils were activated, Pico transfers the result to the
contacts. M8 is now open once more. No new pulse can be generated
until I1 is opened, since M7 is open for as long as I1 is closed. This is
known as a ‘One-shot’ pulse.
How does the value reach the shift register?
When shift pulse M8 = ‘on’, the state of I2 (value) is transferred to
storage position M1. If I2 is switched on, M1 is set. If I2 is switched
off, M1 is cleared via break contact I2.
How is the result shifted?
Pico activates the coils in accordance with the circuit connection 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 switched on. The state of the coil changes
only if the circuit connection up to the coil is enabled. In this circuit,
the marker relay is therefore either set or reset.
The circuit connections of the coils (storage positions) are only
enabled via M8 for one cycle. The result of activating the coils is
stored in Pico until a new pulse changes the state of the coils.
How are all the storage positions cleared?
When I3 is turned on, all the ‘R’coils of storage positions M1 to M4 are
reset, i.e. the coils are turned off. 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 position be transferred?
Use the make or break contact of storage positions M1 to M4 and
program them to an output relay or in the circuit diagram according to
the task required.
Running Light
An automatic running light can be created by slightly modifying the
shift register circuit. One output is always switched on. It starts at Q1,
runs through to Q4 and then starts again at Q1. The marker relays for
storage positions M1 to M4 are replaced by relays Q1 to Q4. The shift
pulse I1 has been automated by the flasher relay T1. The cycle pulse
M8 remains as it is.
00.50
TRG
RES
T1
+
{
S