Blowing CJ1 Comm's Port...

[Sleepy Wombat 27]

Heres the scenario... I have a CJ1G-CPU43H with its associated Power supply and IO etc.... The PLC power supply is a 240VAC type supplied via a UPS. I have a land line based modem on the peripheral port connected via a CS1W-CN118 I have a GSM modem for SMS comm's on the PLC RS232 port.... Each of the modems have their own plug pack power supplies... The modems are in the same cabinet as the PLC.. The modems cable runs are only a few feet. (1 meter (3ft) at most) This scenario has happend twice where the RS232 comm;s chip and the Peripheral comm;s chip needed to be replaced... the rs232 ports on the land line modem and the GSM modem have both blown also... The power supplies are ok to the modems.... The land line modem will ring and answer but of couse not pick up bacause of the blown comm;s ports on the modem and PLC. The GSM modem comm's port is stuffed also however it appears to be working - ie the signal lights flashes as normal...as said the peripererhal port connected the GSM modem via a CS1WCN118 is stuffed also.... I have now connected the GSM modem to the PLC RS232 port and will connect the land based modem to a CJ1W-SCU41 card... hopefully this can isolate the prob to either if this happens again... Has any one every had any experienc similar... The next step will be to place an RS232 isolators between the modems and the PLC ... but this is getting ridiculus.... argh! The modems do not blow the comm;s ports straight away... it could be months/ years... but generally they have blown both ports together..

[svn 0]

I have connected a Siemens GSM modem to SCU21-V1 on RS232C. This is working without problem for last more than one and a half year. Some 15 years back, one Honeywell IPC620-06 port blew up while connected to a PC when the PC power socket got grounding fault. Since then as far as possible I use a pair of ADAM4520 (because at our location we don't get reliable RS232C isolator) to connect to RS232C equipment like weight indicator or other PLC CS1W-CN118 doesn't provide isolation hence I always use a combination of CS1W-CN114 + CQM1-CIF02 (which is isolated) for connection to PC. SVN

[BobB 58]

I had a couple of serial ports blow in the CJ1M series PLCs and they were only ever connected to Omron touch screens. Had to go back to Japan for repair.

[Sleepy Wombat 27]

WTF... back to Japan... at least they were able just to replace3 the comm's chips this time and they work again.. Any explanation of what might of happend to the comm;s ports mate ??

[BobB 58]

Not really and no explanation was offered probably because they were repaired in Japan. I had problems with the Alpha series RS232 ports also but I was lead to believe it was the chip that was being used. I think the chip was Cosel - if I rember correctly. Have you talked to Arif at all Sleepy? He is usually pretty cluey.

[MuttsNutts 0]

Is there a possibility of using opto-isolators on serial comms?

[Eric Apperley 0]

1. Are all the plug packs (power supplies) plugged into the same UPS as the PLC? 2. Can the timing of these incidences be traced to either lightning strikes or major power surges (eg trees falling on lines or major S/C or O/C conditions on the power network) in the area? Often these types of failures are related to differences in earth potentials, especially under fault conditions. With RS232 the TD and RD signals are of course referenced to SG (signal ground), i.e. unbalanced signals. SG should be electrically separated from the FG (Frame Ground). Does the UPS actually provide surge protection when running on AC power? Some of the older/cheaper models don't... Check: 1) Earthing - watch out for earth loops! Don't earth SG to FG! 2) If the incidences can be related to power disturbances add qood quality surge protection and filtering. You can do this yourself by fitting varistors P-N, P-E, N-E plus a small power line filter module AFTER the varistors. The varistors (or the Phase line itself) need to be fused as varistors go S/C on failure! The best solution would probably be optical isolation as pointed out by others.

[Sleepy Wombat 27]

Its a SOLA model 06250700A... online type. have to check on surge protection function.. We have done a site survey to install surge arresters and isolators etc... and it looks as though we are putting in optical isolators among other protective devices around the site... Thank you guys for confirming what i had already thought, i appreciate all the feedback...

[james_applied 0]

Are the power supplys sharing the same 0 volts. What cable are you using? (might be worth posting a diagram)

[PdL 71]

Hi James, the last reply in this topic is well over 2 years old, so I am sure your help is highly appreciated, but I hope for Sleepy it is fixed by now

[james_applied 0]

I dont know quite how i ended up in this post, i may have searched for something and been browsing.