Machine won't go into Auto Mode

I had a client call today that had a Bethel laminate press that they had moved from one factory to it's current location. They had everything back together, and it would work fine if you manually controlled it, but would not go to automatic mode when the operator told it to.

It's controlled by an Allen Bradley SLC 5/03 PLC. The first thing I thought of was a safety interlock connection was not being made.

You see, usually when an Automatic Mode is available, there are checks that the PLC makes to be certain that everything is up and running correctly before it will take full control.

So I fired up RSLogix500 and connected to the PLC. I downloaded a copy of the program off the PLC to the laptop and went online so I could monitor it as it was running.

I told the operator to press the 'auto mode' button so I could see where that input was coming into the PLC, and when I located it, I was also able to isolate the required items needed for it to go into auto mode.

I could immidiately tell that one of the needed inputs never lit up. A quick look at the machine schematics told me that that particular input was for the "Cycle Start" pushbutton. I asked the operator to toggle it so I could see if it did actually trigger the input, and low and behold, it did NOT. hmmm. Wiring problem, I bet.

So I traced the wires from the button to the PLC input module and noticed that when they had re-wired the cabinet during the re-installation, they had broken the connection from the button to the PLC. the wire was hooked up to the wrong point on a distrobution block and couldn't make the connection to the PLC.

So I moved the wire. the cycle start pushbutton started to work, so we tested the auto mode.

It worked like a charm.

The maintinance staff had worked on it for days, and didn't notice the miswired connection. They didn't have the tools to go online with the PLC and watch it operate in realtime, so they couldn't tell what was going wrong.

Chalk one up to experiance, and having the correct tools for the job.

Making RSLinx play nice with other serial apps

Our customers often have many different types of equipment at their facilities. Many want to administer that equipment themselves, since they all have PLCs and CNCs that need programming, tweaking, or backing up.

They buy a laptop and the software, and realize that only SOME of it is working correctly. Very often it is because another program is latched onto the serial port. We see this constantly with Rockwell Software's RS Linx.

By default, RS Linx sets itself up as a service under windows, and is constantly monitoring the serial port for connection to Allen Bradley PLCs and equipment.

Then if you try to run Siemens' Step 7 or Step 5 (or virtually any other serial based comm program), it can't communicate because RSLinx has control of the serial port. The quick fix is to right click on RS Linx down by the clock on the taskbar and close it. it will release the comm port, but when you reboot, it will come back.

A perminant fix to disable the RSLinx service, so that it only runs when you tell it to.

In your start menu, locate the Rockwell folder, look in the RS Linx folder for a program called "RSLinx Classic Launch Control Panel".

You can stop (and start) the service there, and if you uncheck the "always run as service" box, it won't start back on reboot.

A Burkle Hot Press Success Story

REA Technologies was recently presented with the challenge of repairing a Schleicher Rack System for a Burkle hot press. This system had suffered a blown power supply and a CPU that would not boot. There were also problems with the Schleicher input and output modules. In all the rack was comprised of 27 individual units: 12 input modules, 8 output modules, 3 access modules, 2 remote I/O modules, a PLC, and power supply.

Our customer, located in Indiana, had an entire line down due to the failure of this rack system. The urgency of this repair couldn't be expressed enough. In today's economy a manufacturing facility can not afford a single minute of downtime. In addition, downtime also directly affects the employees who are often sent home without pay because the line isn't running.

This was the case for our customer. We here at REA understand how such a situation affects all of those involved. We received the rack Next Day Air on Feb 24, 2009 and shipped it back on Feb 26. This was extremely challenging to do in such a short amount of time due to the number of units that comprised the rack system and the multiple failures it had. The failures were not centralized to any one area.

Our technicians rose to the challenge. The biggest problems we found were cold solder joints on surface mount devices. The power supply had multiple blown parts which we had here in our well stocked parts department. This is particularly advantageous as it eliminates the costly next day airing of repair parts Anyone who works in electronics knows how difficult these type of problems are to locate and correct!

The technicians painstakingly mapped out the circuits and went through every individual unit. They also checked the Eproms and copied them so we would have a back-up for the customer in the vent they were to lose their parameters. We have the capability here to burn replacement Eproms and promptly ship them to the customer. REA has gotten lots of customers back online over the years due to this capability without stepping foot in the facility, saving them money and downtime. The employees benefit by being able to stay on the job and earn money for their families. REA Technologies can most often provide a win-win situation for all concerned.

Contact REA Technologies today for any and all of your industrial electronic repair needs You will find us most accomodating. We are a family owned and oriented business. We look forward to hearing from you.