Bering C Sparky
Lifetime Supporting Member
Carry over from another post, but I was asked a question about how AB One Shots functioned on the AD Forum.
Here is the question I was asked:
I answered the question:
But then I got to thinking........
I have never used OSR or OSF instructions in AB....only the ONS instruction.
Am I right to assume that the OSR and OSF instructions in Allen Bradley generally follow the same rules as far as, the logic on the rung before the One Shot instruction must be true in the case of the OSR and False in the case of the OSF for the One Shot to become True itself for one scan?
I always assumed that they followed the same general rules as the ONS in this way.
But now I see that AD software acts differently and the One Shot is not a unique tag but replicated from others in the program to function more as a one shot XIC or XIO (Rising / Falling) to a specific tag that is used elsewhere in the program.
Do the OSR and OSF instructions in AB at like the ones in AD also????
Or do they follow the same general rules as the ONS instruction????
I could dig out my old AB software and emulator and try it myself but was hoping someone would just give me the answer for free, so I can put this out of my mind and move on.
Thanks in advance.
BCS
Here is the question I was asked:
I'm not familiar with AB. Is the one-shot behavior an attribute of the element itself, rather than the instruction?
I answered the question:
Yes exactly,
Each One Shot is a unique and individual tag. One Shots become True when the logic before them is True. Not when another instruction with the same tag is True elsewhere in the program.
In Allen Bradley, when a One Shot is placed on a rung, it requires all the instructions before it (to its left) on the rung, to be True in order for the Output to the right of the One Shot to become True for 1 scan.
But then I got to thinking........
I have never used OSR or OSF instructions in AB....only the ONS instruction.
Am I right to assume that the OSR and OSF instructions in Allen Bradley generally follow the same rules as far as, the logic on the rung before the One Shot instruction must be true in the case of the OSR and False in the case of the OSF for the One Shot to become True itself for one scan?
I always assumed that they followed the same general rules as the ONS in this way.
But now I see that AD software acts differently and the One Shot is not a unique tag but replicated from others in the program to function more as a one shot XIC or XIO (Rising / Falling) to a specific tag that is used elsewhere in the program.
Do the OSR and OSF instructions in AB at like the ones in AD also????
Or do they follow the same general rules as the ONS instruction????
I could dig out my old AB software and emulator and try it myself but was hoping someone would just give me the answer for free, so I can put this out of my mind and move on.
Thanks in advance.
BCS
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