CCST 42 — Two-Point Calibration Error

Briefing

A technician applies 0 percent and then 100 percent to a transmitter and records the loop current at each point, in hundredths of a milliamp: ZERO_READ_X100 (ideal 4.00 mA = 400) and SPAN_READ_X100 (ideal 20.00 mA = 2000). Report each calibration error as a percent of span, in tenths of a percent: ZERO_ERR_X10 and SPAN_ERR_X10. The span of the signal is 16.00 mA (1600). For example, a zero point reading 4.10 mA is 0.10 mA high, which is 0.625 percent of span, reported as about 6. A result within 1 of the true value is accepted. A low reading is a negative error. Maths is built with Math boxes (SUB, MUL and DIV), or in the Code tab one assignment per line. Multiply before you divide, and hold the in-between product in a DINT.

Objectives

• Exactly 4.00 mA at zero and 20.00 mA at span: both errors are 0
• A high reading gives a positive error and a low reading gives a negative one
• The zero error and the span error are worked out independently

I/O Table

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

1. #14.00 and 20.00 mA → no error

   A perfect transmitter has no error

2. #2Zero reads 4.10 mA → +0.6 percent

   A high zero is a positive error

3. #3Span reads 19.84 mA → -1.0 percent

   A low span is a negative error

4. #4Both points high

   Zero 4.24 mA and span 20.32 mA

5. #5Zero reads 3.84 mA → -1.0 percent

   A low zero is a negative error

6. #6Span error only

   Zero correct, span 20.80 mA