6ES7522-1BL01-0AB0 giving small voltage to LED

Perhaps during manufacturing or shipping, the LED light pipes were slightly offset causing light bleeding over from nearby LEDs??  Does the LED always show dimly lit even if every other DO on the card is off?  If the PLC is in stop mode (assuming STOP action turns off DO's in hardware config), do all the DO's automatically turn off?  If so, what's the LED then?  Still dimly lit?

Is there cabinet lighting that is possibly making it appear dimly lit?

JLA Farhan

I've issue with the LED keep showing small LED light even though the DO card not trigger to energize. When DO trigger the LED will become more brighter. How to eliminate the small voltage current when the DO card not energize/ trigger. I've used F-CPU and thePLC setup as per attached. Looking forward everyone feedback to this. Thanks

Hi,

My reply as below:-

Does the LED always show dimly lit even if every other DO on the card is off?

Yes, its always show dimly lit even though the DO not giving any signal

If the PLC is in stop mode (assuming STOP action turns off DO's in hardware config), do all the DO's automatically turn off? 

I'll check what will happen if I turn the PLC to stop mode. 

If so, what's the LED then?  Still dimly lit?

LED indicator in front of Local Control Panel

Is there cabinet lighting that is possibly making it appear dimly lit?

No. the LED inidicator on the Local Control Panel (refer attached photo)

OHHH leakage current when the DO is off is allowing _some_ visual indication on enclosure mounted LEDs.

In that case, read the specifications for your 6ES7522-1BL01-0AB0 on how much leakage current is present when OFF.  Then add a resistor to drop current flow when off yet maintain enough current flow when ON. You can figure out the proper R value a variety of ways, like EE design-based math, use a POT to find a suitable R value range and pick standard R value in the middle of an acceptable range, google, search this support site, or pay someone to do the math for you (among many other ways).

Or, use the DO to drive an SSR, and use a NO contact on the SSR to drive the LED.

This is electrical engineering, not a DO defect.  Read the specs and design around them.

JLA Farhan

Hi,

My reply as below:-

Does the LED always show dimly lit even if every other DO on the card is off?

Yes, its always show dimly lit even though the DO not giving any signal

If the PLC is in stop mode (assuming STOP action turns off DO's in hardware config), do all the DO's automatically turn off? 

I'll check what will happen if I turn the PLC to stop mode. 

If so, what's the LED then?  Still dimly lit?

LED indicator in front of Local Control Panel

Is there cabinet lighting that is possibly making it appear dimly lit?

No. the LED inidicator on the Local Control Panel (refer attached photo)

What is the potential between the common of the machine lamps and the common (signal ground / M) on the PLC card? Also check the ground / earthing.

A high electromagnetic field may also be a problem. High powered device or frequency generating device may generate a small voltage in the wires. Having the PLC ON completes the circuit for the induced power. -- we do not know your application, so only you can say if it is possible.

Hi,

Thanks for the guideline. yes I found 0.5 mA out put current on the DO card during signal "0" which means there are possibility the led dimly lit. good suggestion also on the adding resistor on the circuit. Thanks again for the guideline.

Have a nice weekend :)

Hi,

Thanks for your fedback. Yes, we did check the earthing and confirm all OK.