Referential Connection Circuit between PLC System and Sensor
Post date:2017-12-22 10:48:53    View: times    
The Application Scheme of Sensor and Data Acquisition System in Industrial Field
I. The Model Selection Based on the Performance of the Analog Signal Sensor
1. Two-wire current/voltage output sensor (No power supply, need load supplies 16-24V power distribution, output 4-20mA/0-5V power).
 
1.1 4-20mA two-wire passive sensor (input model) receives power distributed by current isolated distributor, then connect it to PLC.
As shown in Fig.1, connect positive terminal of distance measuring sensor and weighing sensor with 16-24 VDC power, the negative terminal outputs 4-20mA current.

1.2 4-20mA two-wire passive sensor (input model) receives power distributed by voltage isolated distributor, then connect it to PLC.
As shown in Fig.2, Fig.3, the positive and negative terminals of displacement sensor and electric scale sensor are connected with16-24VDC voltage.

1.3 Two-wire sensor outputs 4-20mA current loop isolated by isolator, then connect it with PLC. As shown in Fig. 6 , the positive terminal of pressure sensor and flow sensor are connected with 9-32 VDC voltage, the negative terminal outputs 4-20mA current.

1.4 Two-wire sensor outputs 4-20mA current loop isolated and adjusted by isolator (avoid conflicts between input and output ), then to do connection with PLC.
As shown in Fig. 7, the positive terminal of temperature sensor and speed sensor are connected with 12-24 VDC voltage, the negative terminal outputs 4-20mA current.

2. Four-wire Current/Voltage (Input/Output) Sensor (Have its own power supply 24VDC, input/output: 4-20mA/ 0-5V)
2.1 Isolated and Amplified by analog signal, four-wire current output mode sensor is connected with PLC.
2.1.1 As shown in Fig. 8, the positive terminal of temperature sensor, humidity sensor are connected with 24 VDC voltage, the negative terminal outputs 4-20mA current.


2.1.2 As shown in Fig.9, the positive terminal of pressure sensor and speed sensor are connected with 24 VDC voltage, the negative terminal outputs 4-20mA current.

2.2 Isolated and Amplified by analog signal, four-wire voltage output mode sensor is connected with PLC.
2.2.1 As shown in Fig. 10, the positive terminal of pressure sensor and speed sensor are connected with 24 VDC voltage, the negative terminal outputs 0-5 VDC voltage.

2.2.2 As shown in Fig. 11, the positive and negative of flow sensor and liquid level sensor are connected with 24VDC power, output 0-5VDC voltage.


II The Connection Scheme between PLC and Sensor

 
The Application Case in PLC (2#: Vout +, 3#: Vout -)
1. In two-wire mode, the negative 2# outputs 24VDC Voltage, 3# receives current, so there are two connection methods:A: 2# is connected with the sensors’positive, 3# is connected with sensors’ negative, the jumper is set to two-wire current signal. B: 2# is at zero gate voltage, 3# is connected with sensors’ negative, and the positive of sensor should be connected with the 24VDC power in the cabinet, the jumper is set to two-wire current signal. (in this case, 2#: Vout+, 3#: Vout-)
2. In four-wire mode, Vout 2# receives current, 3# is negative. In the connection scheme, 2# is connected with the sensors’positive, 3# is connected with sensors negative, the jumper of PLC is set to four-wire current signal. (The advantage of four-wire mode is that when the negative signal of sensor and M in the cabinet is different, it has little effect on the accuracy, because the sensor itself is the recirculating loop of current )
3. The connection method between four-wire sensor and PLC jumper: connect the signal negative with M in the cabinet, the sensors’ positive is connected with 3#, 2# is at zero gate voltage, the jumper is set to two-wire current.
4. Voltage signal: Connect 2# with sensor’s positive, connect 3# with sensor’s negative, the jumper wire of PLC is set to voltage signal.  


 

Latest Technical News
Copyright ©2002-2018 Sunyuan Corporation. All rights reserved. SHENZHEN SUNYUAN TECHNOLOGY CO., LTD. Address: 2nd Floor, Building#6, Dongyi Industrial Park, Zhonghuan Road, Minzhi St. Longhua New District, Shenzhen, 518109, China. Tel: +86-755-83100080 83100110 Fax : +86-755-83116652 Email: sy@sun-yuan.com