DROK 4-20mA Generator, Adjustable Signal Generator, DC 0-10V 0 4-20mA Current Voltage Analog Simulator for Value Adjusting PLC Panel LED Testing

This is a nice tool, and inexpensive. It can be powered by a 24VDC power supply, or I used 2 9V batteries in series. There is one terminal for V-Out, one for I-Out, and one for A- Com. If you do not know what any of these terms mean, this is not the device for you.There are capabilities to edit patameter set for both current and voltage. Another reviewer posted snip of settings and procedure. I used these to get I-Out from a 4-20mA down to a 0-20mA output.Relatively small device, great for portability. Approximately 4" x 2" x 2"I will probably locate a hard case and line it with foam pad to store device.

I needed to prove something at work. I had a rudimentary PLC that sends a 4 to 40ma signal. It used a potentiometer to measure fuel level, and the 4 to 20ma signal output is proportional to that input. I had an unused Analog input on a Caterpillar 4.2 panel. The panel used a 0 to 5Vdc input. Using a 250 ohm resistor, I was able to obtain a volt drop across the resistor in the 1 to 5Vdv range. Using this signal generator, I was able to emulate the PLC's output signal and program a CAT 4.2 panel to read fuel level with a 4 to 20ma signal. I had to prove it on our shop's gen before we could suggest it as an upgrade to any customer's gensets.The device is not accurate when it is shipped. BUT its has trim pots on the backside. These are just to make the display screen read the same as the output. I have not really messed with them, as inacurate display readouts were not something I needed to worry about because I was watching with my Fluke 87V.My needs were satisfied, the output is adjustable, and the price was excellent. If I dabbled more in the world of automation, then I might need something more. But then again, maybe not.

I was ready to chuck this gizmo into the trash and write a one-star review, because I thought it was useless, at first.My mistake was in believing the label that said 12-24 volts. I had connected a beefy 12 volt supply (actually a little over 14 volts). This device didn't work well at all on a nominal 12 volts.But before giving up, I wired two 9 volt batteries together and gave it an 18 volt supply. Whoa, that's the ticket. With an 18 volt supply, it does what I wanted. I'm not looking for super accuracy with a $30 gadget. But I wanted to be able to put out a variable current so I can test some equipment before it's fully on-line. This unit does that well, as long as you provide enough juice. The display isn't perfectly accurate, but you can monitor this with a VoltOhmMeter. I didn't have much success with the calibration pots on the back side of the board, but it works reasonably well if you can live with it.There is no manual with this, so you better know what you want. I connected the 18 volt battery to 2 terminals. Another terminal is common, and there are 2 more terminals. One of these provides a constant voltage, up to a little above 10 volts (relative to the common terminal.) The other terminal provides a constant current up to about 20 mA, relative to the common terminal.The knob will rotate 4 turns, and it varies the current or voltage from minimum to maximum. What isn't obvious is that the tiny switch is changing the DISPLAY from volts to mA. Only the display. The knob changes the output on both the volt and the milliamp terminals simultaneously, regardless of the switch position. Duh, why wasn't that obvious to me?So it's a surprisingly worth while little tool. I wouldn't use this on a mission to Mars, but for general troubleshooting and testing, it's worth the price and then some.

I may HVAC technician and I purchases to help troubleshoot damper motors on equipment economizers

This device looked like a good option for an inexpensive test tool, but it's not. There is no ability to power it from battery, making it useless in the field. The entire device is the circuit board itself, with components soldered on and no other form of stabilizing the parts from damage by bumping against something, also making it useless in the field. There is no way to get power in and measurement leads out other than screwing wires into the terminal block. This is fine for permanent installation, but way too fiddly and dangerous for field testing. Considering how easy it is to blow a 4-20mA circuit by either crossing wires or applying voltage, this is a built-in recipe for failure of your circuit sensors and transmitters. The only way to actuate the control the device to press the PC-mount button component (to switch btwn mA and Vdc output) and turn the PC-mount knob. These are not great ways to activate this device in the field or a benchtop.The more important part is its accuracy, which was off by 0.5V in the voltage scale. I was unable to test the mA scale at all because it just didn't work. There was no output at all. I tested with two different Fluke meters and got the same result. Useless.Lastly, the "box" part is just a mounting platform for the circuit board, so no real thought was put into the design as a tool or as a permanent benchtop tester. Even in a lab environment, you'd want to have this installed in a more usable box or DIN rack.Save your money and get something better designed and actually functional.