PLC not responding

[schmidtpresses]

Hi, I'm using your T100MD+ PLC board and I have encountered a problem. The PLC is not responding, cannot communicate with it, LCD is just blinking a cursor and there are 3 LEDs turned ON on the PCB and they are 1 green and two red labeled as RTC err and Run err. My DC power is dead on 24V, I relpaced the microcontroller with a spare one and EPROM chip which did not change my status. One clue I can give you is that this particular PLC was used in a facility that looses it's power on daily bases and switches to generator (Dominican Republic), and I'm not sure if that had something to do with it. Could you give me some troubleshooting tips? Where to start or what to check? Much appreciated,
Adis

[schmidtpresses]

I just found out that M2017P EPROM got fried. I replaced it with spare and PLC is functioning fine. Where do I get spare M2017P? How can I protect IC from DC power supply transients?
THX

[support]

This has to do with the load dump that are caused by the generator during power up/down.

You could add a Transient Voltage Suppressor across the power supply input to the PLC. E.g.

1N6277AG  - Digikey part #1N6277AGOS-ND  for 12V power supply operation
1N6283AG  - Digitkey part #1N6283AGOS-ND for 24V power supply operation.

We have recommended the above part numbers to several customers and so far there was no negative feedback after they installed the above device. We would also appreciate your feedback on the effect after you have installed the protection diode to the power supply circuit as this would help us recommend to other users who faced with similar situation.

For more discussion about Load Dump effect,  please check the following discussion at our forum.

http://www.tri-plc.com/yabbse/index.php?board=1;action=display;threadid=1213;start=msg3748#msg3748

[benb2000]

Hi,

I installed the 1.5KE24A transient suppression diodes across the power leads comining into the unit. This is upstream of the steering diode feeding the circuitry.

The remedy is not 100%, I have had units returned from the field, after the diode has been installed, where the M2017P has been corrupted, some to the point of not being able to re-program.

I think your firm should develop a special power conditioner module, to allow relable use of a T100MD888+ in an Automotive application.

Our dealer, DCI Inc. in Calgary Canada,  pointed us to a DC/DC converter that they have been trying, we purchased a few, and are trying them as well, so far no field results. Lab tests have been positive.
We are also going to try the DC UPS from http://www.powerstream.com/DC-UPS-1212.htm and add a Sealed Lead Acid gell cell to the system.

My biggest problem with all of this is that the only item to fail is the M2017P.

[support]

This is strange. I would imagine the voltage transient from the power supply would have been absorbed by the TVS.

Is your PLC connected to any expansion board or MD-HMI? One of the signals to the M2017P also goes to the expansion board so it it picks up voltage transient from the expansion connector it could be the reason for failure.