Looking for a simple solution to properly latch the 6/0 latch after the TOF has timed out? When input 2 turns off after 2000 milliseconds, there may be an issue with the DN bit remaining high. Consider using an equal instruction to ensure that if the preset 2000 is equal to the 2000 milliseconds, the output will turn true. It is important for input 2 to remain high, as dropping for longer than 2000 milliseconds should trigger an output. If the DN bit is consistently high, explore alternative options. Your assistance is greatly appreciated.
To optimize your programming in Logix, it's crucial to analyze the timing charts for instructions in the help documentation. In a TOF operation, the DN bit remains active when the preceding logic is true, stays true for the specified timer duration after the rung becomes false, and deactivates once the rung is false and the duration has expired. To ensure the output activates after the TOF operation is complete, use the XIO timer.dn instruction in conjunction with the OTE output. By understanding and correctly implementing this functionality, you can effectively control the timing of your program in Logix.
I had a lengthy explanation in mind, but Robert got there first.
To achieve the desired outcome, consider utilizing an XIO instruction and a TON instruction instead of a TOF instruction. If the Input remains False for less than two seconds, the Output will not activate due to the TON.ACC value not surpassing the TON.PRE value. However, if the Input remains False for more than two seconds, the Output will activate and remain on until the Input transitions back to True.
According to Ken Roach, using an XIO instruction and a TON instruction may be more suitable than a TOF instruction in this situation. If the input remains false for less than two seconds, the output will not activate due to the TON.ACC value not surpassing the TON.PRE value. However, if the input remains false for over two seconds, the output will be triggered and remain on until the input becomes true again. Additionally, Ken Roach expresses a personal dislike for TOF instructions.
Robertmee recommended studying timing charts for instructions in the Logix help to understand the functioning of a TOF. In a TOF, the DN bit remains on while the logic preceding it is true, stays true throughout the timer duration even when the rung goes false, and turns off after the rung is false and the duration has passed. To ensure the output is activated after the TOF completes, the instruction would be XIO timer.dn OTE output. This is essential in cases where the input is consistently high due to the nature of the application. If the input is interrupted for 2000msc, then its DN bit is set. Thank you for the helpful explanation.
Looking at your issue, it's imperative to ensure that your DN bit isn't locking up under certain conditions. One thing you could try is implementing a reset instruction that targets your timer. This can potentially prevent the DN bit from remaining high whenever input 2 turns off after your 2000 millisecond period. Remember, proper feedback wiring and programming are just as crucial to avoid any issues. Additionally, double-checking your conditions for the latching and unlatching can prove worthwhile. Trying out these tips might help resolve your issue.
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Answer: Answer: The issue with the DN bit remaining high after input 2 turns off is that it may prevent the proper latching of the 6/0 latch after the TOF has timed out.
Answer: Answer: To ensure proper latching of the 6/0 latch after the TOF has timed out, consider using an equal instruction to compare if the preset 2000 is equal to 2000 milliseconds, which will trigger the output to turn true.
Answer: Answer: It is important for input 2 to remain high for the output to trigger after 2000 milliseconds as dropping below this duration should trigger the output, and input 2 serves as the trigger for this action.
Answer: Answer: If the DN bit is consistently high, it is recommended to explore alternative options to address this issue and ensure proper functioning of the output activation with TOF timeout.
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