TheWaterboy
Lifetime Supporting Member + Moderator
This would likely pertain to any scenario but in case it matters, here's mine:
I have an array of Dints representing alarm bits, (i.e. DintTag[1].7). The array is used in a program that looks for changes in the array to indicate new alarms have occurred since last acknowledged.The array format is needed to make this processing easier than calling a bunch of separate bits by name. But this format is more clumsy for the HMI to deal with.
For example say the DintTag[1].7 is for a pump fail indication. I created an alias tag called Pump Fail and the SCADA and HMI use that tag making the HMI side of things easier to handle.
But within the logic, Is it better to "drive" an OTE representing DintTag[1].7 with a Base tag directly or can I use the Alias tag "Pump Fail"?
I know that the Alias tag references the memory location of the base tag so they are identical. But if I "Drive" the OTE with the Alias tag when writing the logic , the Base tag is also displayed in the ladder making it self documenting and easier to troubleshoot for others in the system after I am gone.
Is there a potential problem writing it this way or should I drive the base tag instead. The end result to the HMI side is the same, the benefit I see on the PLC side is the self documenting property that occurs.
Opinions?
I have an array of Dints representing alarm bits, (i.e. DintTag[1].7). The array is used in a program that looks for changes in the array to indicate new alarms have occurred since last acknowledged.The array format is needed to make this processing easier than calling a bunch of separate bits by name. But this format is more clumsy for the HMI to deal with.
For example say the DintTag[1].7 is for a pump fail indication. I created an alias tag called Pump Fail and the SCADA and HMI use that tag making the HMI side of things easier to handle.
But within the logic, Is it better to "drive" an OTE representing DintTag[1].7 with a Base tag directly or can I use the Alias tag "Pump Fail"?
I know that the Alias tag references the memory location of the base tag so they are identical. But if I "Drive" the OTE with the Alias tag when writing the logic , the Base tag is also displayed in the ladder making it self documenting and easier to troubleshoot for others in the system after I am gone.
Is there a potential problem writing it this way or should I drive the base tag instead. The end result to the HMI side is the same, the benefit I see on the PLC side is the self documenting property that occurs.
Opinions?