bmillerx94
Member
Hi all,
I come to the forum for a strange encounter with some LED indicators I bought for a project. The LEDs were cheap ones from China, $5 for a 3 pack of yellow, green, and red. Not sure if they are "true" LEDs or not, but they do say LED on the back, with some Chinese writing in addition.
The problem I am experiencing is that the LEDs are receiving some power when connected to the PLC outputs because they light up faintly. When I first wired it up, turned the PLC on, i figured the output were energized from a recent program I wrote to the controller. Well, thats not the case. I cleared the memory from the PLC and wrote an additional program to actually energize the LED outputs. Then they get full brightness.
So it's obvious the LEDs are receiving some current, I just don't quite understand why that is. If anyone could help me out to understanding why they have a dim light when the outputs aren't energized, that would be great.
Heres some more information:
1. This occurs even when the PLC is not powered up.
2. This occurs regardless of switching terminals on the LED
3. A single LED has simply two terminals.
4. The PLC is a CLICK and the LEDs are connected via an additional 120VAC-240VAC discrete relay output module
5. All input and output devices are 120VAC and the PLC is powered with a 24VDC CLICK PSU.
6. All commons are wired to the CPU and the additional output module
7. The LED(s) is wired from HOT120VAC to one terminal, and then out directly to the output module.
Thanks in advance!
I come to the forum for a strange encounter with some LED indicators I bought for a project. The LEDs were cheap ones from China, $5 for a 3 pack of yellow, green, and red. Not sure if they are "true" LEDs or not, but they do say LED on the back, with some Chinese writing in addition.
The problem I am experiencing is that the LEDs are receiving some power when connected to the PLC outputs because they light up faintly. When I first wired it up, turned the PLC on, i figured the output were energized from a recent program I wrote to the controller. Well, thats not the case. I cleared the memory from the PLC and wrote an additional program to actually energize the LED outputs. Then they get full brightness.
So it's obvious the LEDs are receiving some current, I just don't quite understand why that is. If anyone could help me out to understanding why they have a dim light when the outputs aren't energized, that would be great.
Heres some more information:
1. This occurs even when the PLC is not powered up.
2. This occurs regardless of switching terminals on the LED
3. A single LED has simply two terminals.
4. The PLC is a CLICK and the LEDs are connected via an additional 120VAC-240VAC discrete relay output module
5. All input and output devices are 120VAC and the PLC is powered with a 24VDC CLICK PSU.
6. All commons are wired to the CPU and the additional output module
7. The LED(s) is wired from HOT120VAC to one terminal, and then out directly to the output module.
Thanks in advance!
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