I am currently in the process of commissioning multiple units and encountering difficulties with achieving a flying start. The situation involves my Programmable Logic Controller (PLC) using Modbus to regulate a blower motor essential for a heater system from a third-party. The heater system initiates a blower request to which I respond by sending the control word 1151 to start the drive and acknowledging the heater once the blower reaches the required speed. The challenge arises when the heater short-cycles, causing the drive to remain inactive until it fully stops, resulting in an alarm due to the lengthy spin-down process of the large blower. Despite implementing parameters for a flying start, it functions properly only in local control mode and not through Modbus commands. My drive control function block is straightforward - sending 1151 to run and 1150 to stop, without any logic to verify a complete stop before initiating a start. I suspect that 1150 is specifically a ramp to stop command, leading me to question if flying start only operates during coasting (possibly triggered by command 1149).
Please note that in parameter 99.04, the motor control mode does not allow flying start or automatic restart unless parameter 21.19 is set to Vector in scalar start mode. To enable automatic start mode (page 115), ensure parameter 21.02 is set to Scalar in automatic start mode.
According to TWS manual, it is noted that in order to enable flying start or automatic restart in Motor control mode parameter 99.04, Scalar start mode parameter 21.19 must be set to Vector. This can be found under Automatic start mode on page 115. The setting for parameter 21.02 must be Scalar for automatic restart to take place. This was the first thing we confirmed.
After resolving urgent issues, I managed to contact ABB technical support and received a puzzling response regarding the ABB state machine. According to the response, it is normal for the drive to stop before it can be restarted, as indicated by Control Word Off1. However, there is a workaround suggested: setting the initial state as 1150, using 1151 for standard run or jog, and using 1087 to stop by removing bit 6 of the Control Word. This workaround involves monitoring the motor speed and resetting the control word to achieve a shut-off state. One confusion arose regarding the suggested use of commands 1150, 1151, and 1087. The second issue raised was the necessity of a workaround for a feature that should be functioning correctly. Why does the state machine still require a complete stop before restarting, especially if the flying start option is enabled? This discrepancy is concerning. I have reached out to ABB for clarification and am awaiting a response. I will provide a final update once I have a resolution. In the meantime, I welcome any insights or experiences that others may have to share.
After addressing urgent matters, I managed to connect with ABB tech support and received a puzzling response. The initial dilemma I faced was deciphering the specific punctuation placement. From my understanding, 1150 signifies the idle state, 1151 represents standard running or jogging, and 1087 (1151 - 2^6) indicates "run with ramp input set to 0." The suggestion is to use 1151 for running, 1087 for stopping, and either wait for speed feedback to reach 0 before transitioning to idle state 1150, or initiate a restart at any point with 1151. However, the issue lies in the fact that this pertains to a blower motor that should coast to a stop rather than ramp down. The next puzzler is why a workaround is necessary to utilize a feature that is already enabled. If the flying start option is active, why does the state machine still mandate a complete stop before restarting? This discrepancy is quite frustrating and raises questions. I have reached out for clarification and am awaiting a response. I will provide an update once I have a resolution. If anyone else has experience or a functional AOI to share, please do so. On a related note, the topic was unresolved, so here's what I discovered: OFF1 involves coasting to a stop, transitioning to true, and then running from 0 to 1 for a restart. For reference, here is the complete control word. I hope this clarifies the situation for everyone.
In a previous discussion, user Nathan66669 raised an unresolved issue about resolving a particular control word. After some research, it was found that in order to restart, OFF1 must be activated after coasting to a stop, then transition from 0 to 1. Attached is the complete control word for reference. It is important to note that bits 0 through 6 and bit 10 must all be set to TRUE in order to run successfully. Hopefully, this explanation helps clarify any confusion for users seeking a solution to this issue.
It does sound like your system might have some difficulties recognizing when it's safe to initiate a flying start. The blower seems to need to be in a specific 'state' in order to accept start commands. You mentioned that your drive control function block doesn't check if the blower is fully stopped before trying to start it again, and this may be a part of the problem. You could consider implementing some sort of feedback mechanism in your PLC to check the status of the blower before sending the start command. Alternatively, adjusting the part of your code that dictates stop and start logic could also rectify the issue. As for the ramp-stop command suspicion, it would be best to consult the drive's manual or seek manufacturer support. Hope this helps!
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Answer: - To troubleshoot the flying start problem, ensure that the parameters for flying start are properly configured in the drive settings. Verify that the Modbus communication between the PLC and the drive is functioning correctly. Check if the drive control logic includes a complete stop verification before initiating a start command.
Answer: - The drive may remain inactive when the heater short-cycles due to the lengthy spin-down process of the large blower. This can trigger an alarm because the drive needs time to stop completely before it can be restarted. Consider adjusting the drive parameters or implementing logic in the control function block to handle short-cycling situations.
Answer: - The flying start feature on the ABB ACS580 drive is designed to allow the drive to start the motor without waiting for it to come to a complete stop. It is typically used to reduce downtime and improve operational efficiency. Verify if the flying start feature is configured correctly and if it can be triggered by specific Modbus commands such as 1149.
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