Greetings. I am currently facing challenges and seeking guidance in navigating a complex situation. Apologies in advance for the lengthy explanation. The issue at hand involves a recently implemented batching system equipped with advanced features typically found in a Rockwell based DCS. Plant PaX 5.0, FTVE SE, and FT Batch are all operational. The project was initiated due to increased demand amid the Covid pandemic, but encountered delays due to supply chain disruptions, leading to strained relations between the integrator and my employer. This resulted in several unresolved issues, such as integrating the RO Water supply loop into PlantPax. As the sole Controls specialist at my workplace, I lack the support of colleagues or prior experience to turn to for assistance. While I have successfully deciphered the faceplate/AOI relationship and can replicate existing functionalities and incorporate new elements seamlessly, I am currently facing a roadblock in managing two RO flow loops. Controlling the pumps using the PVSD object is straightforward, as is using the PPID object for proportioning valves. However, I am facing difficulties in utilizing the PPID to regulate the pumps based on the flow meter readings. Although I have connected the flow meter AI to the PPID as per standard practice, I am struggling with programming the PPID output to the PVSD. Despite knowing that the PVSD can be scaled, I am uncertain whether an AO is necessary in this scenario. Any guidance or examples would be greatly appreciated. Thank you for your patience in reading through my challenges.
Is it truly this straightforward? How does manual control work on the VFD faceplate? Is it controlled through the PID faceplate?
While I am unfamiliar with the functionality of the built-in 5.0 objects, I can provide insight into how the 4.x objects function. In manual mode, control is primarily managed through the faceplate. Nonetheless, the PLC can also regulate entry into manual mode by utilizing the PCmd_Oper bit.
Cheeseface mentioned that they are not familiar with the built-in 5.0 objects but can explain how the 4.x objects work. The manual mode can be controlled from the faceplate, but entry into manual mode can also be managed by the PLC through the PCmd_Oper bit. My main concern is how to connect the "speedref" from the PID AOI to the Drive AOI. I am converting it to a percentage, where 60hz equals 100%. Do I direct the CVOut from the PPID to the PVSD and then to FreqCommand? Or should I go through an Analog Out object first? If manual speed control is needed, would it have to be done from the PID faceplate? It seems that either faceplate can set a speed command.
It seems you are interested in the different oper/prog frequency commands. The PID output is already in percentage and needs to be directed to the PSet_SpeedRef. Operators should control the manual mode of the PID instead of the VFD to enable bumpless transfer when switching back to auto mode. The VFD faceplate can also control via OSet_SpeedRef, but utilizing the PID manual mode is the preferred option.
77nomad raised a question about the simplicity of controlling a VFD through the faceplate in manual mode. Is the PID faceplate involved in this process? The output should be connected to CM_SC_912_01_Out_SpeedRefDataTypically. In programming, using the "Out" prefix for signals is common for linking blocks or outputs. "Val" represents the values that are visually appealing, making it easier for users to read, comprehend, and display on the screen.
Hey there, I can certainly appreciate the complexity you're dealing with right now. I've only encountered Rockwell's PlantPax system a few times, but I'll do my best to help. You're on the right track in utilizing the PPID to regulate the pumps based on the flow meter readings, and connecting the AI to the PPID should be a standard move. Now, concerning the programming of the PPID output to the PVSD, an AO might indeed be necessary. Consider this: the AO will be responsible for actuating the pump according to the PID output. Remember to properly scale the AOI to match the pump's operational range. Be patient with the process, apply small adjustments first, and observe the behavior. I hope this helps a bit, and don't hesitate to follow up if you need more clarification. Best of luck with your project!
From your description, it sounds like you're on the right track with connecting the AI to the PPID. I'm wondering though, have you checked the main parameters like P-Gain, I-time, and D-time? Misconfigurations can occur there. Regarding the connection from the PPID output to the PVSD, normally I think it should work without AO, as the PPID output is already a variable that the PVSD can interpret. Just make sure the PVSD is scaled properly as per the pump's range of operation. If after checking these you're still having trouble, it may be helpful to reach out to Rockwell's support team; they've assisted me with similar complex issues before.
It seems like you have a good handle on many of the controls, which is commendable given that you're handling it all by yourself. Regarding regulating the pumps based on the flow meter readings, you already have the right idea to interface between the PPID and the PVSD. An AO might indeed serve your purpose here effectively, as you can use it to transmit a 4-20 mA control signal to the pump VFD from the PPID output. You simply need to set up your AO to take values directly from your PPID object; essentially, the PPID output should be your AO's input. However, every architecture can vary slightly, so it would be helpful if you could share some more details about your setup.
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Answer: Answer: The main challenges include difficulties in utilizing the PPID to regulate the pumps based on flow meter readings and struggling with programming the PPID output to the PVSD.
Answer: Answer: Controlling the pumps using the PVSD object and proportioning valves using the PPID object is straightforward in a batching system.
Answer: Answer: Seeking guidance from forums, online resources, or contacting Rockwell support may be helpful in such situations.
Answer: Answer: It's uncertain whether an AO is necessary in this scenario, and further clarification or examples may be needed for programming the PPID output to the PVSD.
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