Episode 9 Column
Now we only have two episodes left in our comic. Actually, we’ve covered all of the main points that we wanted to convey throughout episodes 1-8, and episodes 9 and 10 will mostly focus on potentially useful tips. This includes DC power supply “interfaces.”
As you know, the main application for laboratory DC power supplies is powering circuits. However, these “laboratory” power supplies are aptly designed with experiments in mind and thus require interchangeable output. You could even refer to these power supplies as “arbitrary voltage/current generators.” These instruments are vital for testing the dynamic characteristics (how circuit behavior changes under various conditions) of your DUT in numerous tests including “input voltage fluctuation tests.” How would your 5V circuit react when exposed to 4V and 6.5V input voltages? These types of experiments are made easy with programmable DC power supplies. But what if you want to conduct a test with periodically fluctuating voltage (ex: 5V±10%)? Although you’d think that this could be simulated by turning the voltage knob manually, this would be impossible to repeat with high accuracy for long periods of time. This is why we have automated the process (sometimes with sequencing features) with external controls (interface).
In the past, remote control of DC power supplies was mainly conducted by inputting analog signals (voltage, resistance, contact points) through the power supply control terminals (this is still implemented). Although this method is quite simple, it is somewhat lacking in the accuracy and precision department, which is why Hewlett-Packard developed the “GPIB” interface for measurement communication of automated test systems. At the time, GPIB was the worldwide standard for automated measurement communication. Several years later, IBM’s personal computer (PC/AT) burst onto the scene, and computers equipped with RS232C (serial port) interface were widely used. The connection landscape changed in the 2000’s, as interfaces such as USB and LAN (ethernet) became the major communication methods. Use of USB and LAN interfaces in particular have become widespread in anywhere from benchtop experiments to large-scale systems due to their versatility and “plug and play” simplicity.
GPIB is considered obsolete by some but is still highly reliable when used with older technology, whereas RS232C still has solid support because of its compatibility with external controllers such as PLCs. This means that modern DC power supplies must support both legacy and modern interfaces, which can make product development quite difficult. Especially in the modern age where product miniaturization is paramount, trying to fit both old and new connectors onto the rear panel can feel like solving a complex puzzle. In fact, the actual arrangement of DC power supply connectors played a significant role in the history of interface transitions and applications.
This brings us to our final episode. Is Minami going to be okay? How did the new product plan work out? Are sparks beginning to fly between our two protagonists? Find out (and learn a little bit) in our last episode!!
