No power when modules are plugged into the second half of a 10 slot backplane. Same modules work when plugged into slots on first half of backplane. Here is the kicker.. I have changed the backplane and I get the same result.

Novice here hoping for help. Thanks in advance.

 

Did you correctly size the CPS PSU?
When you say no power to backplane second half, what exactly do you mean, no LEDS on modules, or
modules not reading / writing I/O. I assume this is a single rack system.

 

An existing 10 slot backplane had 9 modules running. A DDI module in slot 6 was bad so the plc was powered down and the module was replaced. When the power was restored, There is no sign of power to the last 5 slots of the backplane. I have swapped modules from the last five into the first five slots and they all light up. However they will not light up if I return them to their original slots. The backplane has been swapped to confirm no problems with the backplane.

 

I don't know Modicons well, so this is just kind of a general question. Is there a 5-slot rack, and could the processor configuration have become corrupted during the power cycle and now it thinks it's talking to a 5-slot rack, and fails to communicate with the modules in the higher slots? Weird idea, but the rack and modules seem to have been eliminated as the problem, and it did occur concurrent with a power cycle.
--
Steve Myres, PE
Automation Solutions
(480) 813-1145

 

Dear Anonymous,

Another wild guess. Is the power supply a separate module? Could you try replacing it? It is possible that due to power output limitations on the PS module, there might be two output points inside the module, probably having onboard fuses, feeding the two halves.

Tomy Zacharia

 

The Power Supply has been replaced.


On July 27, 2006, Tomy Zacharia wrote:
> Another wild guess. Is the power supply a separate module? Could you try replacing it? It is possible that due to power output limitations on the PS module, there might be two output points inside the module, probably having onboard fuses, feeding the two halves. <

( Complete thread: http://www.control.com/1026224246/index_html )

 

The configuration was the trick! I was puzzled how I could have had 5 slots with power when the backplanes come in the following slot versions: 2,4,6,8, and 10... In any case the project was reloaded to the CPU and all is well. I want to thank everyone who had input my problem and I hope to be able to return the favor some day. THANKS!