Micrologix 1200 COM 0 fried

[PLC Boy]

I am having a problem with a Micrologix 1200 the com0 port keeps going out when I plug into my panelview C1000 please help. I have gone through two PLC's now and i am still not sure what is causing it. The system has been up for a couple weeks with no problems but today the com port went, had a new one couriered in installed and it, lasted about ten min. before the com port went on this one.

 

[sthompson]

I am having a problem with a Micrologix 1200 the com0 port keeps going out when I plug into my panelview C1000 please help. I have gone through two PLC's now and i am still not sure what is causing it. The system has been up for a couple weeks with no problems but today the com port went, had a new one couriered in installed and it, lasted about ten min. before the com port went on this one.

Please give us the exact part number for the Micrologix 1200, and C1000 HMI.

Stu.....

 

[Gil47]

In addition to what STU asked also add the part number of the inter connecting cable.

 

[PLC Boy]

The controller is a 1762L40BWA the panelview is a 2711C-T10C and the cable is a 2711-CBL-PM10. I checked the cable pinout and the cable tests good, I am wondering if I have a bad serial port on the panelview or if I am getting stray voltage from someplace else. I am looking for any possible explanations for the communication port frying.

 

[geniusintraining]

and the cable is a 2711-CBL-PM10. I checked the cable pinout and the cable tests good, .

I would still replace the cable, its a cheap fix (cheaper) do you have to have one that long? have you check the cable for cuts?

 

[TomekPLC]

Is your communication cable terminated somewhere along the way between PLC and HMI?

 

[PLC Boy]

no the cable is not terminated just runs straight through. It needs to run from operator console to tthe cabinet where the PLC is located thus the reason for the 10 meter cable.

 

[TomekPLC]

Is your 10 meter communication cable run next to the high power wires?

 

[PLC Boy]

It is run next to alot of wires and I wouldn't doubt that some of them are high power. I removed the cable and checked for nicks and cuts looked good but ordered a new one anyway and will reroute cable so that it is isolated from the other wires in case they are inducing voltage.

 

[Clay B.]

If you still have one of the PLCs with the blown com port have AB check it out. Getting these reconditioned is a good idea since the the Comm port seems to be the only thing damaged.

Also double check your grounds on both the panel view and your PLC. If you are inducing voltage from higher voltage circuits your gound should bleed this off.

If possible run the comms cable away from the higher voltage stuff anyway. This is just good pratice and prevents alot of nuisance issues.

 

[Gil47]

I believe the PLC and the PV run from 24 volt DC

Are they both on the same power supply. ?

Are they on 2 different power supplies . ?
that have been earthed, in such a way that one has its positive earthed and the other has its negative earthed.

Both would still run on there own 24 volts but collectively you could get 48 volts and the comms ports may be seeing this issue which the PLC and PV dont see as an issue

 

[PLC Boy]

Both are running off of the same power supply and use the same ground, I have a new panelview and controller that I am going to install tomorrow with a new cable routed differently than before hopefully it works and stays working this time. In addition I got a new 1200 with a serial port dedicated to the panelview so hopefully if it does burn out I can communicate through the configurable Com 0 and alter my system to run using standard PB inputs until I track down the problem.

 

[Plastic]

Make sure your ladder program does not have an ACL (Ascii Clear Buffer) Instruction.

You can "brick" a ML1200. The user typically would want to use ACL when using the only COMM port in ASCII mode, then expect DCOMM for program modification.

Problem is, ACL will render the COMM port useless EVEN in the DCOM mode. ACL effects both COMM User mode and COMM System Mode.

 

[Gil47]

Beside where you plug for the RS232 cable on a ML1200 there is a cover over two trim pots and below them is a very small toggle pushbutton, that toggles the comms protocol if there are two protocols setup .

Now this is a very long shot but did someone push that button and turn the RS232 comms to some other comms setup there by knocking you off.