Utilizing an AB 2085-OF4 module to regulate process current control for multiple VFDs, I have the channels set at 0-20mA but am controlling the output within a 4-20mA range. All 4 channels of the card are in use. Despite proper configuration, channels 0, 1, and 3 do not show any current output to the VFDs, while channel 2 does operate within the desired 4-20mA range. While using a Fluke 789 process meter, attempts to measure the card's output yield no results on any channels, including the functioning one. However, switching the card's output to voltage allows for successful readings. This discrepancy raises questions regarding the functionality of the card. Despite no fault indications from the diagnostic LED, the inability to output current remains a concern. Any suggestions on troubleshooting or resolving this issue would be greatly appreciated.
When operating in incurrent mode, what is the output voltage for different current settings? If the output voltage consistently measures above 5-10 V, it is important to verify the loop resistance at the receiving end for accuracy. This will ensure optimal performance and prevent potential issues.
This module still experiences a glitch where removing the wire can disable the channel output in the 4-20mA configuration. It is uncertain if this issue also affects the 0-10V configuration. To resolve this, I re-downloaded the program, though I am unsure if there is a less disruptive method to reset it. Rockwell ought to address this anomaly, as it deviates from the usual behavior observed in the 1769 series of controllers.
rbarbee shared that there is a glitch in a module where removing the wire disables the channel output in the 4-20mA configuration. It is unknown if this issue also applies to the 0-10V configuration. To resolve this issue, rbarbee redownloaded the program, suggesting that Rockwell address this uncommon behavior in the 1769 series of controllers. One solution is to create a push button on the HMI to toggle a bit that will reset the control bit of the specific AO card (3848) back to 0 after a 2-second delay. An image is provided for reference.
I recently encountered this problem. Is this a common issue? Is there a more effective solution than simply having a button on the screen?
Today I encountered an issue with the reset button in the image above. I modified it to automatically reset the analog card every time the pump is activated, ensuring that the 4-20 signal is sent out without any open wire faults. In our upcoming projects, we plan to connect AOs to isolators to prevent the occurrence of open wire faults. It is disappointing that Rockwell has not addressed and resolved this problematic design flaw.
It sounds like you're having quite an issue with your AB 2085-OF4 module. My first concern would be whether the setup of your output ranges properly match across both your card and your VFDs. As you mentioned, your card behaves as expected when switching to voltage output, pointing to a possible mismatch in current range settings. One thing you might consider attempting is a calibration process for each of your channels. Given that no faults have been identified by your system's LEDs, this could potentially rectify any unnoticed discrepancies. It's also worth checking the wiring to ensure everything is properly grounded and no shorts exist. Lastly, if all else fails, the card could be defective. In this case, reaching out to the manufacturer could be of value.
This indeed sounds like a perplexing issue. Something you might want to look into is whether there are any power supply problems that are affecting the current output. Additionally, I would suggest double-checking the wiring and the grounding of your module to rule out those potential issues. Conducting a factory reset on the card might be worth considering if you are still unable to resolve the problem. However, if your card is still not functioning correctly after differential diagnosis, I would recommend contacting Allen Bradley's support. Given there are no fault indications, it's possible there might be a fault in the card itself that requires replacement or professional service.
It sounds like you've done a thorough job setting up the AB 2085-OF4 module, but I'm curious if you’ve double-checked the wiring and connections for channels 0, 1, and 3 to ensure there are no loose connections or shorts that could be affecting the current output. Also, confirming that all channels are properly configured in the software settings is crucial—sometimes a simple oversight with parameters can lead to such issues. If everything looks correct and it's still not working, you might want to test with another current loop device to rule out a fault in the VFDs themselves. Additionally, checking for any firmware updates for the card could also help resolve potential compatibility issues. Good luck, and I’d love to hear how it turns out!
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Answer: - This issue might be related to configuration settings, wiring problems, or potential faults within the module itself. Troubleshooting steps could involve checking the configuration parameters, verifying the wiring connections, and considering the possibility of a faulty module.
Answer: - The discrepancy in channel performance could point towards specific channel configuration differences or potential hardware issues. Investigating the configuration settings for each channel and conducting further diagnostics on the module may help identify the root cause.
Answer: - The inability to measure current output could indicate issues with the module's current output circuitry, the meter setup, or potential communication problems. Troubleshooting steps might involve verifying the meter's settings, checking for proper connections, and assessing the module's output functionality under different conditions.
Answer: - When facing a situation where the module shows no fault indications but fails
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