WorldWide Drilling Resource

Trending by Britt Storkson Owner, P2FlowLLC We’ve all seen what is “trendy”...the latest style or wide- spread interest in something. Trends are patterns of events, like a warming trend in the weather. While this may be of inter- est to those who follow social media, trending is also a very use- ful tool for computer controls. Why? Because “trending” identifies patterns of behavior which can determine what is and isn’t proper operation so the computer can make corrections. For ex- ample, data integrity is critical for the proper operation of any computer. By data in- tegrity, we mean what we put into a memory stays there and isn’t altered in any way. All computer memory is simply voltage impressed or “stored” on silicon. If our digital system voltage is +5 volts, it means a logic “1” will measure 5 volts, and a data logic “0” will measure 0 volts. A data “write” is where we place data in a memory location, which has a unique number. A data “read” is where we copy data out of a memory location, leaving that data unchanged. Data is usually organized as bytes. A byte is 8 bits in a row, numbered from bit 0 to bit 7, with bit 0 being at the far right and bit 7 being at the far left. It’s like we write numbers starting from right to left. Each bit contains a voltage which is either 0 volts or 5 volts. This is computer memory and it is very fast, cheap, and durable. Since all data is ones and zeroes stored in a memory, we cannot “write” a “1” into memory location and “read” a “0” out of that same location sometime later, or vice versa. What we put in memory must stay there unchanged until we change it. While computer memory is very good at retaining data, like anything, it isn’t perfect and sometimes we would like “backup” data that is critically important to what we do. One way to do this is to “write” the critical data value to more than one data lo- cation. Say we “write” the same data to five different memory locations. If we “read” the same value out of each of the five memory locations, we can be certain of data integrity. The data has been retained correctly. But if four of the five locations read the same value, yet one does not, we reject the one “nonconforming” value and rightly assume the remaining four values are the correct ones. The logic behind this is, if a majority of the data “agree”, then we can be certain the data is correct. We are reading a data “trend”. We use this technique for our water pump controls to make sure critical values are maintained. We don’t want our “high pressure off” to be set by the user at 60 psi only to have a corrupted memory “read out” 80 psi or more. Another “trending” technique is to test and/or measure things not once, but many times to make certain the measurement is valid. With our water pump controls, we measure the pressure input not once, but several hundred times a second. We then make sure the pressure trend over time is valid before changing the state of the pump (off or on). The last thing we want is for a pump to “slam on” and “slam off” rapidly in an uncontrolled manner. As with most anything, if you want to make sure it’s right, check it over and over again against something you know is right. With microprocessors, this is fast, easy, and good programming practice. Britt Britt Storkson may be contacted via e-mail to michele@ worldwidedrillingresource.com If you want to make sure it’s right, check it over and over again against something you know is right. 3"- 0)'! +#0* /'! /,,). '+ ./,!( '4#. 6 /, 6 +(. ,1* + 13 -"#+ ))#3 5 2 - 0!&*$% !,* 5 - 0!&*$% $-,+/'#-+#/ !,* ,"#) '4#. /#+/ + " #+"'+% 11 NOVEMBER 2015 WorldWide Drilling Resource ®