Dl305 cpu error & analogue input fault

[sttchui 1]

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 i have 2 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?? D3-10B-1 - 1 CPU340 - 1 F3-04ADS - 1 F3-04DAS - 1 D3-16NE3-1 2 D3-16TR - 1 F3-04ADS - 1 D3-16TR - 1 D3-08TRS-1 - 1 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

[rlp122 4]

First thing is to get rid of the voltage on the grounds before someone gets hurt. Grounds should never have more than a few tenths of a volt AC or DC.