How to set the PLC output points to better control the load.
Let's talk about it, mainly including grouping output, matrix output, parallel output and so on.
The details are as follows:
1. Grouping Output. When the two groups of loads will not work at the same time, can be switched through the external switch or electrical contact controlled by PLC, so that a PLC output point can control two different loads working at the same time.
2. Matrix Output
To make a load work, as long as it is located in the row and column corresponding to the output relay is switched on.
For example, when Y010 and Y004 are connected at the same time, KM1 is electrically attracted.
It should be noted that: when only the corresponding output relay of a row is connected, the corresponding output relay of each column can be connected arbitrarily;
Or when only the corresponding output relays of a certain column are connected, the corresponding output relays of each row can be connected arbitrarily.
Otherwise the load will be mistakenly switched on.
Therefore, when using matrix output, the load that is connected at the same time must be arranged on the same row or in the same column, otherwise it will not be controlled.
3. Parallel Output loads with the same on-off state can be connected in parallel and share one PLC output point (considering the load driving ability of PLC output points).
For example, PLC-controlled traffic signal lights have the same on-off rule in the corresponding directions (east and west, south and north). The output points can be saved by half after the corresponding lights are connected in parallel.
4. Load multi-function a load to achieve a variety of purposes.
For example, in a traditional relay control system, an indicator light indicates only one state.
In PLC control system, the use of PLC software is easy to achieve the use of an output point control indicator light and bright, so you can use an indicator to represent two different kinds of information, thus saving the PLC output point.
5. Some output signals do not enter the PLC system in some relatively independent, relatively simple parts can be considered without PLC control, direct use of relay control can be.
6. Using output points to expand output points is similar to using output points to expand input points. It is also possible to use output points to share the output content of a set of output points.
For example, when the output port is connected with a number of LED7 segment code display, if the direct connection is used, the required output points are many.
At this time, the circuit of 3 can be used to use the time-sharing of the output points to light up the multi-LED7 segment code display one by one.
In the circuit shown in 3, CD4513 is a special common cathode 7 with latch and decoding functions
7. Segment code display driver circuit, two CD4513 data input terminal A ~ D share the programmable controller's four input terminal, A is the lowest, D is the highest bit.
The LE end is the latch enabled input end. At the rising edge of the LE signal, the BCD data lock of the data input end is stored in the in-chip register, and the number is displayed after decoding. LE is a low level, and the number of the display is not affected by the data input signal.
Obviously, the output point occupied by an n-bit display is P=4+N.
When Y004 and YOO5 are connected respectively, the output data will be sent to the upper and lower CD4513 respectively.