Application of multi-channel DC electronic Load in PLC testing

PLC is a digital computing controller used in automatic control, which can load, store and execute control instructions. As a general control device that integrates computer technology, automatic control technology and communication technology, PLC has been widely used in many industries such as automobiles, electricity, steel, mining, petroleum, and chemicals.

PLC test items generally include input and output, programming logic, communication, fault diagnosis, etc. As a key component for realizing control execution, the driving ability and load accuracy of the output unit directly affect the working performance of the PLC. Therefore, PLC output unit testing has also become one of the focuses of manufacturers.

● PLC test requirements and traditional test solutions

Take the world's TOP1 PLC manufacturer S as an example. S is a global leading electrification, automation and digitalization company. It provides leading solutions to the industry in the fields of power generation and transmission and distribution, infrastructure, industrial automation, drive and software. The company has been in the top 500 in the world for many consecutive years. In the early stage, the customer needed to test the output unit performance of its S series PLC, and put forward the following test requirements:
01 Multiple unit modules need to be tested simultaneously: The output of a single PLC is 8 channels, and some models of PLC have dozens or even hundreds of channels. When multiple PLCs need to be tested, this puts higher requirements on the integration of the test equipment;
02 High-precision, wide-range programmable test equipment is required: The rated output of the PLC is 24Vdc/750mA, and the output range is 20.4V~28.8V. Generally, the test device needs to accurately set and read back the output current and output voltage.

In the early stage, customer S used cement resistors and traditional desktop electronic loads to test the output unit performance, which had problems such as insufficient output accuracy and a large amount of test equipment occupying space.
Insufficient output accuracy: Cement resistors are prone to resistance drift due to heat under long-term working conditions, which cannot guarantee the stability and accuracy of the test value;
Test equipment occupies space: The traditional desktop load 19-inch 3U standard frame supports up to 8 channels, but the test of only 2 PLCs requires 6U space.

● NGI multi-channel high-precision test solution

For customer S, they had some testing problems in the early stage. The NGI-provided N6180 series multi-channel micro-power DC electronic load can perfectly solve their problems.

19 channels can be integrated in 3U space, and the space occupied by the same number of channels is only 1/3 of the traditional desktop load;
The current is a dual-range design with an accuracy of up to 0.02%+0.05%F.S., which can ensure that the setting and readback error will not exceed 1mA when the load current is 750mA, which also meets the testing requirements of the full range of high, medium and low-end PLCs;
Supports high-precision voltage readback, without the need to use a digital multimeter to measure the output voltage, saving costs in procurement and wiring.