Tze,
It sounds to me like you might be over-complicating this with too much “relative-terminology”. It really is a very easy concept to understand. Maybe this will give you a better picture.
HARDWARE VERSION OF R-S
A complete “Hardware” version of an R-S device consists of 4 elements:
“S” = SET-Input
“R” = RESET-Input
“Q” = OUTPUT
“Q’” = “NOT-Q” Output
In Hardware, it is sometimes necessary to “positively-assert” the absence of an output signal. That is, if “Q” is Not ON, then, turn on a signal to “positively assert” that “Q” is OFF. This is accomplished by simply applying the “Q-Output” signal to an Inverter. The Output of this Inverter is called “NOT-Q”. Both outputs, “Q” & “NOT-Q”, physically exist and are available for use.
“NOT-Q” will always be the opposite of “Q”.
If “Q” = 1, then “NOT-Q” = 0.
If “Q” = 0, then “NOT-Q” = 1.
SOFTWARE VERSION OF R-S
When speaking in terms of a PLC, a complete “Software” version of an R-S device typically*** consists of only 3 elements:
“S” = SET-Input
“R” = RESET-Input
“Q” = OUTPUT
(*** I say typically because your information seems to contradict that. It appears that you can select which output you want to use, "Q" or "NOT-Q"... is this so? Seems weird.)
Typically, in a PLC, the absence of the output signal is “asserted” simply, and only, by the absence of the signal. That is, if “Q” is Not ON, then “NOT-Q” is IMPLIED. If you wish, you can very easily create a “pseudo-positive-assertion” by means of the following:
Q
--|/|-----------( NOT-Q )
.
In a PLC “R-S Logic-Block”, the state of “Q” determines whether, or not, the block provides “power-flow” to the next element in the rung. If “Q” = 0, then “power-flow” is disabled; the following element does NOT execute. If “Q” = 1, then “power-flow” is enabled; the following element DOES execute.
In some PLC’s, “Q” can be referenced. The state of “Q” can then be determined by means of the --| |-- and --|/|-- symbols. This allows for subsequent activity (in later rungs) based on the current state of “Q”.
THE DOMINANT FACTOR
The Hardware version of an R-S device does not respond predictably in the case where both the SET-Input and the RESET-Input are ON. The Truth-Table for a Hardware R-S device indicates that an input combination of S=1 and R=1 is NOT VALID.
The Software version can be
forced to respond predictably. The response, in the case of S=1 and R=1, is determined by specifying a “Dominance Type”.
If the “Dominance Type” is specified as “SET DOMINANT”, then, in the case where S=1 and R=1, the Output “Q” is “SET”; that is, “Q” = 1.
If the “Dominance Type” is specified as “RESET DOMINANT”, then, in the case where S=1 and R=1, the Output “Q” is “RESET”; that is, “Q” = 0.
TRUTH TABLE
When trying to analyze the Truth-Table for either the Hardware Version –OR- the Software Version, it is easier if you simply look at the “S”, “R”, and “Q”; ignore the “NOT-Q” for now.
The Truth-Table on the Left shows the responses of a "SET DOMINANT" R-S Logic Block. The Truth-Table on the Right shows the responses of a "RESET DOMINANT" R-S Logic Block.
In Case-1, the Question Marks indicate that the states of "Q" and "NOT-Q" are what they were after the last operation.
Cases -1, -2 and -3 are identical. These cases indicate the response of the R-S device regardless of the "Dominance Type" and regardless of whether the device is a Hardware Version or a Software Version. This is because there is no logical conflict.
The effect of the "Dominance Factor" shows up in Case-4.
In the Left Truth-Table the “Dominance Type” is specified as “SET DOMINANT”.
In Case-4, where S=1 and R=1, the Output “Q” is “SET”; that is, “Q” = 1.
In the Right Truth-Table the “Dominance Type” is specified as “RESET DOMINANT”.
In Case-4, where S=1 and R=1, the Output “Q” is “RESET”; that is, “Q” = 0.
"NOT-Q"
Now, for any particular case, if you want to know the state of "NOT-Q", simply INVERT the state of "Q".
The two Truth-Tables, shown above, should be all you need to have all of the relevent information.
You said...
1) Reset Dominant with only Reset Output
2) Reset Dominant with only Set Output
3) Reset Dominant with a Set Output and Reset Output
4) No set/reset overrides with a Set Output and Reset Output
5) No set/reset overrides with a Set Output
I personally think 1) and 5) have similar functionality if reversing the input bits.
My interpretation...
It appears that you are saying that you can select which output you are going to use... seems a little weird to me.
1) Reset Dominant with only Reset Output
In this case, if S=1 and R=1, then "Q" = 0 and "NOT-Q" = 1
-AND- in this particular case, "power-flow" is determined by the state of "NOT-Q".
2) Reset Dominant with only Set Output
In this case, if S=1 and R=1, then "Q" = 0 and "NOT-Q" = 1
-AND- in this particular case, "power-flow" is determined by the state of "Q".
3) Reset Dominant with a Set Output and Reset Output
In this case, if S=1 and R=1, then Q = 0 and NOT-Q = 1
-AND- in this particular case, "power-flow" is determined by...???
This one is confusing. Are you sure that your terminology is correct?
This makes me wonder if this particular logic-block is designed to NOT provide flow to a next element.
4) No set/reset overrides with a Set Output and Reset Output
In this case, if S=0 and R=1, then...??? RESET "over-rides"???
"Over-rides" what???
Again, this one is confusing. Are you sure that your terminology is correct?
5) No set/reset overrides with a Set Output
In this case, if S=0 and R=1, then...??? Q = 1???
Again, this one is confusing. Are you sure that your terminology is correct?
I personally think 1) and 5) have similar functionality if reversing the input bits.
I can't speak to this because I don't understand Item-5. Nor can I understand this question... entirely.
Comments on your Tables...
Table-1: RESET Dominant with only RESET Output.
If Reset Output implies using the "NOT-Q" output, then, the Table Output should indicate "NOT-Q" instead of "Q". All of the output values should be inverted.
Table-2: RESET Dominant with only SET Output.
This Table appears correct.
Table-3: RESET Dominant with SET Output and RESET Output.
This Table appears correct.
Table-4: No Set/Reset Over-rides with a SET Output and RESET Output.
Seems not to make any sense. At any rate, Case-4 in this Table is wrong. "Q" and "NOT-Q" should NEVER be equal!
Table-5: No Set/Reset Over-rides with a SET Output.
Again, seems not to make any sense.
Maybe after reading this you can take another look at your source. Then, maybe, you might be able to develop a different (better?) description.
Even if you do figure it out, I hope that you come back and provide an explanation.