PLC how to differentiate between leakage and source input -

How to differentiate between leakage and source input

PLC brand is numerous, the market has both Siemens, mitsubishi, etc in high market share of big brand PLC, there are more than two hundred kinds of small type PLC. But no matter what kind of PLC, the digital quantity input module has two different connection mode: source input mode and leakage input mode. This article today, let's talk about what is the input source type? What is input leakage type? What's the difference between the two connection?

input (the so-called 'source type 采购输入) ', refers to the public end into the current from the module, the connection mode of flowing from the module of input channel. The public end of the input source type as positive ( A total of anode) 。

source type of input can be equivalent to the external connection battery input module, the positive pole of the battery is connected to the module of public side, the current flow from the positive pole of the battery module within current, flow from input channels to the switch. When the switch is closed, the electric current to flow through the switch back to the cathode of the battery.

digital quantity input module of the channel has optical coupling circuit and to prevent short circuit, don't have to worry about closing switches can cause a short circuit.

'leakage model input ( 下沉的输入) ', refers to the current through the external switch, since the channel from the module to the module inside; After the internal circuit, the connection mode of outflow from the public. In leakage model input, public side as power cathode ( Common cathode) 。

leak dry cell type input is equal to the module external connections, the public end of the dry cell cathode connection in the module, the anode is connected to one end of the switch, and then from the switch at the other end is connected to the input channel, and then through the internal circuit module from public flowed back to the cathode of the battery.

why do you want to distinguish the source type input or input leakage type?

main reason is that some of the PLC controller manufacturer of digital module only support one of the input or input source type. Use of such a module, must according to the module type wiring.

, for example, mitsubishi A series PLC AX40/41/42/50/60 and Q series of QX40/41/42 input module supports only source type, and mitsubishi A series PLC AX80/81/82 and Q series QX80/81 type of input module supports only way.

some modules of PLC manufacturer, for example, Siemens S7 - 1200 SM1221 digital quantity input module and CPU module itself, IO digital channel integration, namely support input source type, type and leakage input. In this module can be according to the project design of habit, select the source or leakage input connection mode. This type of PLC can be either out of current public end, also can flow into the current ( PLC both public side can connect the anode of an external power supply, also can connect cathode) , and has the characteristics of the source input circuit input circuit and the drain, so we can let the input circuit is called hybrid input circuit. As a source input, public termination power of the cathode; As input, the leakage public termination the anode of power supply. In this way, can according to the needs of the scene to wiring, wiring work to bring huge flexibility.

here to be sure, mitsubishi and Siemens about 'source input' and 'input' leakage circuit division on the contrary, the above is according to the division of mitsubishi method to introduce, in use process should pay attention to this.

Siemens S7 - 300/400 series PLC of the dc input module for leakage input (mostly Public termination external power of the cathode. Note: according to the division of SIEMENS method) 。 In S7 - The 300 series PLC, only SM321 ( - - - - - - IBH50 - ) Input module type for the source input ( Public termination is. Note: the dividing method of SIEMENS) ,S7 - 400 series PLC, there is no source input module.

small PLC S7 - All 200 input module is for hybrid input form. In large projects is not recommended, so the input form while convenient wiring, but easy to cause confusion among the power supply. An external switch signal input circuit connection and PLC and PLC external input signal, in addition to like button some dry node signal, some sensors provide NPN and PNP open collector output signals. Stem nodes and PLC input module connection is simpler, here basically no longer compose. For the different PLC input circuit, what is the use of NPN input or PNP input sometimes feel disoriented. Here mainly introduce the two input and PLC input circuit connection.

it is because of the PLC input module circuit form and the diversity of external sensor output signal, we in the PLC input module before connection to fully understand the type of PLC input circuit and sensor output signal of the form, only in this way, to ensure that the PLC input module wiring is correct, for the follow-up of the PLC programming and debugging work to lay a good foundation. CAD part of the wiring diagram:

Coolmay is the unique producer of plc manufacturers and related products.
To be the safest, most progressive domestic plc manufacturers, relentless in the pursuit of customer and employee excellence.
Shenzhen Coolmay Technology Co., Ltd. knows how important it is to offer optional extras, such as plc manufacturersprogrammable control systems to provide quality products for customers.
We utilize our expertise to develop services that add value at each phase of theplc manufacturers development cycle. We evaluate and implement new strategies in response to changing customer profiles and market conditions.
Though the cost of these sustainability initiatives as plc manufacturers can be high, harnessing the power of an ethical supply chain to appeal to conscientious consumers can be a smart move both ethically and financially.