DL305 Analogue input, Help & suggetion needed urgently

Hi,

I have DL305 series PLC using DL340 CPU & analogue input card F3-04ADS, which have been running for few years without any major problem, until recently

Problem

1) The CPU run indicator will run normaly before any operation start, but when we try to run the operation after few step, the CPU run indicator will turn off, then the CPU indicator will turn. Everything come to halt. As i look through the manual it more related to hardware problem, as far as i know we didnt change or add anything new hardware to the PLC. i have replace with new CPU , base & IO yet sometimes this problem still occur!

Now the CPU running stable, sometimes the analogue input card goes hairwire.

2) The Analogue input F3-04ADS(0-10VDC setting) which i have to 2 card inside my base(slot 1 & slot 6). i found the 2nd card(slot no 6) the input always show 4095 which are the maximum analogue value without any voltage(OVDC) or when the wiring attach to it is remove. We have to replaced the card & everything work for a day,now my card again showing same error which i have to replace with another card, & it run back normal again. i have check power supply 10VDC is giving a correct DC supply

i check the supply AC voltage to the CPU base is 110VDC(L& N) but when i compare it to L & E i getting 250-300VAC which abit strange. So i replace the supply power only for CPU with different supply 110VAC & when i compare the ground is getting around 79VAC

Could it be noise problem or floating current causing this problem??? anyone have any solution or idea to solve this problem?or could it be the power budget excedded??

Base-10B - 1
CPU340 - 1
F3-04ADS - 1
F3-04DAS - 1
D3-16ND2-1 2
D3-16TRS - 1
F3-04ADS - 1
D3-16TRS - 1
D3-08TRS - 1

thank you

Regards

sttchui

whats connected to the analogue inputs?

Hi tripper,

All the analogue input is connected to a variable resistor & there is a supply votlage 10VDC connecting it.

it is to control the speed of a motor, it was working like this for few years before.

connecting the analogue input just 2 wire

1st wire the reference voltage(0-10vdc) the other wire the com. 0VDC

The input card module is actaully D3-16NE3 instead D3-16ND2-1, my mistake

thank you!

regards
sttchui

are you able to run the machine without the variable resisters connected to the AI card (forcing the values), I'm thinking u have a field wiring/device issue. water in junction boxes does funny things.

Hi Tripper,

i dis-connect the terminal of the wiring from the analogue module, still it showing 4095(decimal) i try force the value to zero but it just would not change, this happen to the fault card(2nd analogue modeule card), this is the 3rd time it happen this weekend, i notice it will only last like day,then the card will show 4095 then i could reset it or do anything, all the channel 1 to 4 all showing same value, i could not detect or smell any burnt mark on the card itself. i though maybe the base it fault butwhen i try new card on it work for new card but the old one still show the same problem


The other one which located on the 1st slot, yes i can change it to any value or anytime i wish.which they share the same power supply 10VDC

i will try on the field device if it have water inside.

Thank you again!!

Regards

sttchui

Sttchui, Sorry I should have looked at your part no., the D3-16NE3 is a digital input module not analogue?, how have u got the pots wired to this? http://www.automationdirect.com/static/specs/d316ne3.pdf,

hi trpper,

Sorry for the misunderstanding, i am talking about the F3-04ADS,

In the earlier post i mention for the digital input is D3-16ND2 which is actaully D3-16NE3, i thought it might help to calculate the power budget it may have exceeded, but i try the formula according to the manual, it is within its range

my PLC module
D3-10B-1 - 1
CPU340 - 1
F3-04ADS - 1
F3-04DAS - 1
D3-16NE3 - 2
D3-16TR - 1
F3-04ADS - 1
D3-16TR - 1
D3-08TRS-1 - 1

still have problem with this analogue input module, i can't afford keep burning my card out after a day!

Thank you!

Regards

sttchui

i think just found out why my CPU keep tripping from Run mode to program mode & the CPu indicator light on. It only happen when my ground cable is connected to the CPU after i start running my other application.

When i turn off the AC power supply to the PLC, & check the AC supply, my multimeter is show 0VAC, but when i checking compare to Ground i getting like 258 VAC which why i getting shock when i disconnect the cable. i not sure where this source coming but i think most probably this cause the CPU error.

anyone have same problem like this before? Is there anything i could prevent this from happeing againin future?

thank you

Regards,

sttchui

You really need to find the source of that voltage on the ground wire and get rid of it. Voltage on a ground wire is a big problem and needs to be addressed.

well icky812, i did find the source of the voltage, it is one of those cable damage during other installation, which come in contact with the 600VAc bus bar.

after i removed it, it is still running until now, hopefully non other thing is damage to the PLC