I am facing a unique challenge in running a PF755 from the IO over ethernet, which presents its own set of obstacles. The system is integrated into a multi-stage exhaust fan setup for emergency equipment, where I need the hard-wired system to always override ethernet commands. However, the issue arises when an ethernet connection may not be reliable. I require the IO terminals to take precedence over EIP commands in controlling the drive's speed at either 20 Hz or 60 Hz using interposing relays. Despite having an emergency override for a single speed, I am exploring options to ensure the IO terminals override ethernet control smoothly. I have sought advice from Rockwell support and considered using Devicelogix to manipulate parameters for a more predictable drive behavior. By masking off certain sources using the 32x parameters, I aim to prioritize DI logic commands over ethernet speed references. The goal is to seamlessly integrate the drive into our control system while ensuring that the IO always overrides ethernet commands without direct intervention in the PLC programming. Testing will be crucial to verify the effectiveness of these adjustments and address any potential issues that may arise. While there may be alternative approaches to achieving the desired outcome, I am committed to finding a solution that aligns with the current system setup. Any suggestions or insights from fellow members would be greatly appreciated as I work towards optimizing the drive's performance and reliability in this unique scenario.
The Allen-Bradley 755 drives offer the convenience of DeviceLogix programming for PLC functions, located in slot 14. An example of this feature in action is a site using two PF755 drives to control a dredger's slew operation. These drives can be configured as either a master or a slave, or operate independently, all controlled through DeviceLogix programming. Each drive is equipped with multiple IO cards for enhanced functionality.
I previously utilized a similar approach with a PowerFlex 525, though it has been some time. If I recall correctly, I employed the purge function for setting up the hardwired run controls. Refer to the drive manual for instructions on how to use the purge function to assist you with your setup.
ASF recommended using the purge function in the powerflex 525 drive manual to configure hardwired run controls. However, if you need to set frequencies with digital inputs or through ethernet, this method may not work. A constant frequency is required for the emergency override feature.
ASF recommended utilizing the purge function in the PowerFlex 525 drive manual to configure the hardwired run controls. Considering the use of DeviceLogix, the purge function can be employed with digital inputs to adjust the speed reference. Refer to the drive manual for detailed guidance on setting up purge and optimizing device integration.
One of my specifications was to configure a digital input for purging on a PF525 drive, with a purge frequency set at 50Hz. When operating in purge mode, the purge frequency takes precedence over other speed references. This functionality is likely similar on the 755 drive.
It certainly sounds like you're facing a tricky situation with the IO overriding the ethernet commands. I like the route you're considering with 32x parameters and Devicelogix for masking off unnecessary sources. I've worked on a similar setup in the past where prioritizing DI logic over EIP commands worked quite well. However, I would also suggest looking into fallback settings within the PF755's drive parameter list. You can specify a set 'fallback speed' that the drive should resort to when it stops receiving a command from an EIP, effectively making your hard-wired system the ultimate fail-safe. Remember, Rockwell's free Connected Component Workbench software has a ton of resources that can help you navigate and fine-tune these settings. Best of luck in finding the optimal solution here.
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Answer: - To ensure that IO terminals override Ethernet commands in controlling the drive's speed, you can consider manipulating parameters using Devicelogix and masking off certain sources using the 32x parameters. This approach aims to prioritize DI logic commands over Ethernet speed references, allowing for seamless integration into the control system.
Answer: - To optimize performance and reliability in such a setup, it is recommended to work with Rockwell support and explore using Devicelogix to manipulate parameters for a more predictable drive behavior. Testing the adjustments made to ensure IO always overrides Ethernet commands smoothly is crucial to verify effectiveness and address any potential issues.
Answer: - Yes, you can implement an emergency override for a single speed with a PowerFlex 755 Drive and prioritize IO terminals over Ethernet commands by manipulating parameters using Devicelogix and masking off certain sources. This approach aims to ensure that IO always overrides Ethernet commands without direct intervention in the PLC programming.
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