I have limited experience with GE 90-30 PLCs and recently encountered a brake press issue at a customer's site. The GE 90-30 PLC in question is equipped with an IC693CPU350 processor. Upon connecting online, I noticed that approximately half of the I/O and M bits were highlighted in red, indicating that they may be forced. The customer does not seem to have connected with the PLC or have the necessary software or trained staff. Have you come across a similar scenario before? Any advice or recommendations would be highly valued and appreciated.
I have never encountered instances of bits being forcibly manipulated without reason. Could any of these forced bits be connected to the issue that prompted your visit to the machine? Bits may remain forced due to negligence from startup personnel or maintenance staff, which is not ideal. In GE PLCs, forcing a bit does not directly control its on/off state but removes it from program control, including I/O service. The internal bit %S0011 serves as a marker for forced bits. One possible explanation for numerous forced bits could be the use of a generic program by the machine builder with multiple options. Bits related to unused options may be forced but left in a non-impacting state on machine operation. While this is not recommended, it may have been a quick fix implemented for specific reasons.
In response to Steve Bailey's query about forced bits in a PLC program, it is important to address the potential issues that can arise from leaving bits in a forced state. This situation can occur due to oversight by startup personnel or maintenance technicians, and while it may not directly turn a bit on or off in GE PLCs, it does remove program control. The presence of forced bits like %S0011 could be a result of using a generic program with multiple options, some of which may not be in use but are still forced in the program. When inspecting a machine with forced outputs and inputs, it is crucial to have a clear understanding of the program logic. In this case, the presence of a Bend Wizard control system connected to the PLC adds another layer of complexity. While the program may be relatively small and there is an electrical print for reference, the forced items in the program could be affecting the functionality of the Bend Wizard in controlling the brake press. Comparing this troubled machine to an identical one operating correctly with the same PLC and program highlights the importance of revisiting the customer to remove all forced bits. This step may help in troubleshooting and resolving the issues affecting the machine's operation.
Have you verified if this Programmable Logic Controller (PLC) was previously in operation and functioning correctly? Make sure to review the configuration settings to determine if it is programmed to reload from flash memory in case of program loss in RAM. If the PLC was shut down due to a depleted battery, it may have switched to a saved program containing the necessary forces.
The report showed that the brake press was functioning correctly until last Thursday. Although not a new machine, maintenance did replace the PLC battery quickly, without any extended downtime. Using Proficy 8.5 on an older computer, where can I access the configuration information? I attempted to flash an EEPROM but the option was grayed out while offline. It seems there may not be any flash memory available. It appears I may have mistakenly searched for flash memory while online, as I am unable to locate that option in my offline version.
To access the CPU module in Proficy Navigator, simply expand the Main Rack and double click on it. Within the module, there are two options to choose from: RAM (default) and PROM which refers to flash memory in the case of the CPU 350. When downloading to the PLC, there is an option to write to Flash memory as well. Selecting "Write all items to Flash" likely copies the RAM data to Flash memory, suggesting that the backup in Flash memory may include the force status information.
From your description, the issue indeed seems to be related to forced inputs/outputs or internal coils (M). It's quite common to observe this while working on GE 90-30 PLCs. For a temporary fix, you can manually unforce these elements (considering it won't disrupt the plant process), but for a long-term solution, my suggestion would be to tweak the logic or ladder diagram such that direct assignment is not used. This will prevent the PLC from forcing I/O and M bits. Of course, it's thoroughly advisable to train the customer’s staff on PLC programming and operation, or have them invest in a professional programmer for routine maintenance. This equipment can be tricky to handle, and inadequate knowledge about the system can lead to serious faults in the long run.
I faced a similar issue a while back with a different GE machine. It sounds like someone might have forced the inputs/outputs during testing or troubleshooting and forgot to remove them afterward. You might need to check each individual I/O and M bit that's been forced and remove it manually. In terms of software, I highly recommend getting Proficy Machine Edition; it's specifically designed for programming GE PLCs and should make your job easier. Plus, investing in training for their staff would ensure problems like this are caught and dealt with more efficiently in the future.
It definitely seems like you're dealing with a tricky situation! I've faced a similar issue before. Check if there are any faults or errors in the processor status LED's. If the forced I/Os are not necessary for your operation, I would recommend removing them and seeing how the system responds. It's also critical to back up the program before making any changes to safeguard against unintended consequences. Remember that availability of trained staff is crucial when dealing with PLC's, so your customer might want to consider training their employees or hiring experienced maintenance staff for these systems. It's always better to apprehend these issues before they escalate, to prevent costly downtime.
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Answer: 1. What does it mean when I/O and M bits are highlighted in red on a GE 90-30 PLC with an IC693CPU350 processor? - When I/O and M bits are highlighted in red, it typically indicates that those bits may have been forced or overridden in the PLC program.
Answer: - To troubleshoot this issue, you can review the PLC program to identify where the bits are being forced and make necessary adjustments to ensure they are following the intended logic.
Answer: - In such cases, it is recommended to provide training to the customer's staff or offer remote support to assist with troubleshooting and resolving the issue effectively.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.