Introduction to the ControlLogix Processor
The ControlLogix Processor is the controller of an automation system. This is where we store the program that automates industrial systems. Although we can place the ControlLogix processsor in any slot of the chassis, traditionally we place it in Slot 0. We program the processor using RSLogix 5000 (renamed to Studio 5000 in version 21).
The L6x processor has a serial port on board which we might use to communicate with a laptop, panelview terminal, or other devices which commonly use the DF1 protocol, or ASCII for communication. The L7x processors have a USB port for communication.
The battery retains the memory when the processor looses power. When replacing the battery, be sure the processor has power, or it will loose it’s program. In some cases, we must power down to open a cabinet to access the processor. If this is the case, be sure you have a backup of your ControlLogix project before replacing the battery in a processor that is has no power. You will loose the program, and have to download the project again using RSLogix/Studio 5000. On the L7x and L8x processors, you will notice an “Energy Storage” feature. This is a capacitor that will eliminate the need for a battery in most cases.
Status Indicators
There are several status indicators on the processor:
Left side
Batt: This indicator will be solid red if the battery is low or missing. Be sure to replace the battery as soon as possible if this indicator is on. Be aware that in some systems, we may not use a battery.
Force: Forcing simulates field jumpers (to some extent). If the Force light is flashing amber, forces are installed, but not enabled. In contrast, a solid amber force light indicates that forces are enabled in the processor.
Run: If the run light is solid green, the processor is running the program. If the Run light is not illuminated, the processor may be in program mode, or it has no power.
Right Side
IO: The I/O light is normally solid green in a running system. If the I/O light is not lit, the processor is not trying to connect to any I/O in your system. If the I/O light is flashing green, then you have a problem with at least one I/O Module. Go online with the processor in Studio 5000. In the Controller Organizer window on the left side of your screen, scroll down to the I/O Configuration tree. A caution icon will be on the module you are having a problem with. Right click the module, and go to the properties. The connection tab will give you a description of the problem.
RS232: This indicator will flicker or flash as data transfers across the serial port.
OK: The OK light should normally be solid green. A solid red OK light will usually indicate a hardware issue. You can try to cycle power, or re-seat the processor, but if it’s a critical system, I would recommend replacing the processor. On the other hand, if the OK light is flashing red, then a software fault has occurred. To get a description of the fault, go online with the processor using Studio 5000. In the online toolbar (usually at the top left of your window), you will see that the processor is faulted. Hit your pull down tab, and select “Go to Faults”, or “Go to Error”. This will give you a description of the fault.
Note: If you have an L7x or L8x series processor, you will see an AlphaNumeric data display for diagnostics information.
Keyswitch:
If you lock the keyswitch into RUN mode, you cannot create tags, download to the processor, or modify logic. Basically, you can only change the value of existing tags. On the other hand, if the keyswitch in PROG (program) mode, the processor’s program is not running. If the keyswitch is in REM (remote) mode, then you can perform online edits, change the mode of the processor from your PC, and download to the processor. Be aware that if you download to your processor, your system will likely shut down.
Replacing the Processor:
The procedure for replacing the processor will vary between different locations. In general, though, to replace a processor, be sure you have the latest backup of the Studio 5000 project. Next, replace the processor, and be sure to connect the battery on the new processor if applicable. Open your project in Studio 5000 (this will have a .ACD extension). Be sure you have a correct communication path. You can build the path under Communication | Who Active on the menu bar. Then select Download. Most likely, you will want to be communicating of USB or Ethernet as the DF1 Serial connection on the L63x processors and earlier is very slow. Now, Studio 5000 will ask to flash the processor with the project revision. Then the download will take place. Flashing the processor over DF1 may take a couple hours! Ethernet will just take a few minutes.
If a server or utility is not setting the clock, you will also want to set the clock manually. Go to Controller Properties. Then in the online toolbar, this is the icon beneath your keyswitch, or right click the controller in the I/O tree and select Properties. At this point, set the clock on the Date/Time tab while you are online with the processor.
Summary of the ControlLogix Processor
In short, the processor controls your entire system. If your system is completely down, it’s a good idea to check these processor status lights. By using RSLogix / Studio 5000 and the status indicators on the processor, you should be able to troubleshoot your equipment very quickly.
Obviously, if your processor has a battery, be sure to include battery replacements as part of your PM. On the other hand, if you have a capacitor module, such as with the L73 and higher processors, you do not need to replace the battery regularly.
Keep in mind that if you have a major fault on the processor, you will need to get a description of the fault. Do this before you clear the fault. That way, you can track down what caused the fault.
— Ricky Bryce