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Useful Applications for Electronic Loads (3)

USB Flash Drives Make a Comeback

This is the third instalment in a series covering fun facts and applications for electronic loads.

Do you use USB flash drives?

In this instalment, I will discuss USB flash drives. When these “thumb drives” came out (it was about 10 years ago that they really took off) I thought they were the best thing since sliced bread. In those days, rather than being connected to LANs (Local Area Networks), PCs were generally used on a stand-alone basis. In order to transfer data to another computer, I often used a type of ubiquitous removable media called a floppy disk. Because a single 3.5-inch floppy disk holds a mere 1.44 MB (!) per side, when transferring a large file, I would split it into sections (there were tools for that) and copy each section onto a separate floppy disk. Finally, I would load the disks one by one into the target computer to recreate the file. I might as well be describing how we used to wash clothes by hand in the old days!

The first USB flash drives had capacities in the tens or hundreds of megabytes, but in no time at all, drives came out that could store several gigabytes of data. These days, there are flash drives that can hold several terabytes of information. However, despite the convenience of flash drives, after a certain point, their high-capacity and convenience caused them to become maligned by business users. The reason: security. Flash drives allow anyone to copy large volumes of data with ease by simply plugging them into a computer’s USB port. This made them the subject of criticism over concerns about the leaking of internal information. I believe this led business users, who until that point had allowed flash drives to be used freely, to either discourage the use of the drives, or require that they were encrypted. Nowadays, with LANs a ubiquitous part of business environments, the copying of data onto removable media has become less common. You probably have some flash drives you no longer use in a corner of your drawer at work. In this article, I’ll propose ways to put your USB flash drives to good use that involves electronic loads.

Digital Interfaces─A Refresher

Before I explain how flash drives can be put to good use, let us reacquaint ourselves with the digital interfaces currently used in power supplies and load devices. If you know this already, you can skip this section.

Power supplies and digital loads are increasingly coming out sporting comprehensive digital interfaces. While some applications still require analog interfaces due to their superior response, the number of users who, choose digital interfaces when building systems because of how easily these interfaces can be connected to other measurement devices is definitely on the increase. Major digital interface standards include RS232C, GPIB, USB, and LAN (LXI).

RS232C is the serial port that used to be fitted as standard on many computers, and because of this, many measuring devices provide an RS232C port. You can still see many examples of these ports used in systems controlled by programmable logic controllers, for example in applications where analog I/O signals are used to sequence tests, or a serial connection is used for device configuration purposes. RS232C only supports short-range communication and one-to-one connection, and this led to the release of the expanded RS422A (1:10) and RS485 (32:32) standards.

The GPIB (General-Purpose Interface Bus) standard was invented by Hewlett-Packard (now Keysight Technologies) in the 1960s to allow measuring equipment to be connected to personal computers, and initially went by the moniker “HBIP” (Hewlett-Packard Interface Bus). In 1975, GPIB became an international standard when it was approved by the IEEE (Institute of Electrical and Electronic Engineers) under the name “IEEE-488”. IEEE-488 is known for its high noise tolerance and ability to support for both star and daisy-chain topologies, with up to 14 devices able to be connected to the same bus. Its drawbacks are the large size of the connectors and the need to buy a separate interface board for your PC (at considerable cost).

LAN is currently the most common interface type. With LANs already being well established as hardware devices, the measuring industry decided to create a standard for the control of LAN-port equipped measuring instruments: LXI (LAN eXtention for Instrumentation). Incidentally, Kikusui is an informational member of the LXI Consortium. Ethernet (LAN) is expected to become the standard bus type in future due to its superior isolation and support for long-distance communication, both of which are made possible by pulse transformer technology. You may have seen the “LXI” logo on the front panel of a Kikusui device: all products released by Kikusui in the future will generally support LXI.

Finally, there is the USB, or Universal Serial Bus, whose superior connectability has led to its inclusion in many measuring instruments. The USB standard actually comes with a lot of hassles, like the need to check the vendor ID, product ID, and serial number before connecting. But USB ports are as ubiquitous as LAN ports. USB does have its disadvantages, including easily-pulled-out cables, flimsy connectors, and low-noise tolerance. These can make it seem less suited to professional use than the LAN standard (LXI), but USB beats its competitors hands down for convenience, and I believe it is perfect for those who want to start testing straight away, or just need to check some commands.

USB Ports on Kikusui Devices

As you may know, there are two types of USB port: the Type-A port, which is mounted on the host (the PC) and the Type-B port, which is mounted on the device itself (the power supply or electronic load). Some newer Kikusui devices are in fact fitted with type A (host) ports. For example, the PCR-LE series of AC power supplies and the PLZ-5W series of electronic loads have Type-A USB ports on their front panels (Photograph 1). These interfaces are designed to be used by USB flash memory sticks for the purpose of firmware updates (the PLZ-5W series can actually be connected to a USB keyboard as well).

Photograph 1. Type-A USB port on PLZ-5W series electronic load

These interfaces can also be used to connect storage devices to add extra memory capacity. While the electronic loads in the PLZ-5W series can store a maximum of 20 setup configurations in their on-board memory, this number can be boosted by adding a USB flash drive. Setup memories contain all information pertaining to mode of operation, range, configuration settings and other settings, and can be transplanted into other PLZ-5W series devices to reproduce a device’s settings.

To save settings on a flash drive, simply select the destination memory (.info file) and press “Save”, as if you were saving to onboard memory. A summary of the saved information can be reviewed by pressing “Property”. (Photograph 2)

Photograph 2. Memory screen

It is also easy to recall stored information by selecting the desired memory file and pressing “Recall”. Additionally, you can use USB flash drives to save and recall the table values used in ARB (arbitrary waveform generation) mode, external controls, display information, and even ABC preset memories. USB flash drives can be renamed, allowing the user to choose more intuitive filenames. These drives can be renamed on a PC as well, by inserting them into the USB slot. You should note, however, that double byte filenames (such as those comprised of Japanese characters) cannot be read by the PLZ-5W, which will display “???” instead.

Uses for USB Flash Memories in PLZ-5W Series Electronic Loads

If you have a spare flash memory in a corner of your drawer, why not use it to share setup information for your PLZ-5W electronic load? For example, by using flash memory, an employee wanting to share data on test conditions with a coworker in a remote location is able to convert the data in question into an email attachment. The file used is extremely small, making it no problem to send by email. The recipient then simply transfers the file onto a USB flash drive and inserts it into the PLZ-5W to instantly reproduce the settings.

Even when transferring settings between two different models in the PLZ-5W series, settings will be loaded unchanged without problem, provided they fall within the scope of the settings offered on the recipient device. The PLZ-5W series also allows the saving of ARB mode tables, enabling you to share and use samples and templates without the use of a separate application (such as Kikusui’s Wavy).

USB flash memory can also be used to save and share external control settings when, for example, loading settings into a charge/discharge system. As long as the default settings are saved first, they can be easily restored, even after reconfiguration for a system upgrade, simply by recalling the original memory. When using a USB flash memory in combination with on-board memory, it is a good idea to decide on a standard naming convention, e.g. make “00.info” the file for default settings, and “11”, “12” and “13” the files for standard test settings.

The advantage of USB flash drives is that they are easily renamed, and I believe it is this characteristic that has led to these drives becoming used by such a wide range of applications. The PLZ-5W series of electronic loads is compatible with USB flash memories of up to 32GB in capacity (in FAT32 format). I encourage you to try them out if you have a chance.

TEXT BY
Yoshinori Hara
Senior Staff, SE Section, Solution Business Promotion Department

[Major achievements in product development]
Custom-ordered charging/discharging power supply devices, charging/discharging power supply devices PFX20W-12 and PFX2000 series
Direct current stabilized power supply PMR series, power supply controller PIA4800 series
Custom-ordered charging/discharging systems (e.g. PFX2500 series)
Custom-ordered power supply systems, custom-ordered electronic load systems, and custom-ordered fuel-battery evaluation systems

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