Codes for Real-time Checks and Failures

Commands that reference the Codes for Real-time Checks and Failures

Some commands use these codes to identify which real-time check(s) should be performed for a particular SPC standard:

• • Python command stdspc.rtcheck

  • Template commands for XML and the Record Buffer

  • Template command SETRTCHK

Other commands use these codes to identify which real-time failure(s) occurred in one SPC data record:

• • Python command dataspc.rtf.calculatertfvalue()

  • Python command dataspc.rtf.value

  • Python command statspc.data.rtf()

  • Python command inspect.cursubi.ni(idx).rtfvalue

  • Template command RTF_STATUS

Table of Codes for Real-time Checks and Failures

Each real-time check / real-time failure has a numeric value:

Creating one number to represent multiple real-time failure codes

Multiple real-time checks - or multiple real-time failures for one data record - are represented by adding the individual failure codes together. 

Example 1:

To set up real-time checking for both "X-bar above control limit" (1) and "R above control limit (4)", you should specify the number 5 (1+4).

Example 2:

To set up real-time checking only for control limits and specification limits, you would calculate the final value like this:

Combined failure number = (X-bar above control) + (X-bar below control) + (Range above control) + (Range below control) + (X above spec) + (X below spec)

Combined failure number = 1 + 2 + 4 + 8 + 1024 + 2048 = 3087

Bitwise "or"

When summing values to produce a Combined failure number, you can use a "Bitwise or" in your Python code or Template code to ensure that each value only gets added one time. The symbol | is used to perform this operation.

For example:

Python code to add the number 1024 ("X above spec") to a variable sum_failures (that contains an intermediate sum of failure codes) could be written like this:

sum_failures = 1024 | sum_failures

The result:

If 1024 had already been added to the sum_failures variable, then the value of sum_failures would not change.

If 1024 had not yet been added to the sum_failures variable, then sum_failures would be updated to equal its original value + 1024.

Looking for one real-time failure code in a Combined failure number

The easiest way to determine whether a Combined failure number contains a specific failure code is to use a "Bitwise and".

Bitwise "and"

When querying a Combined failure number for a specific failure code, you can use a "Bitwise and" in your Python code or Template code to find out whether that failure code was added to the Combined failure number. The symbol & is used to perform this operation.

For example:

Python code to check for the number 1024 ("X above spec") in the variable sum_failures (that contains the sum of the failure codes) could be written like this:

if (1024 & sum_failures) == 1024:

print "Data failed the test for X Above Spec"

else:

print "Data did not fail the test for X Above Spec"

The result:

If 1024 had been added to the sum_failures variable, then the operation 1024 & sum_failures would return the number 1024.

If 1024 had not been added to the sum_failures variable, then the operation 1024 & sum_failures would return the number 0.