Martel Electronics 320 - Manual (Page 48)

This shows that the pressure input to the transmitter is
at +0.00% of scale, and the milliamp output is 1.25%
low. If the % of scale reading is not 0%, you can
press the Zero Key to acquire a new zero reference.
Change the zero adjustment on the transmitter until
the % error reading is 0%. Now apply pressure to the
transmitter and Model 320 and adjust the pressure
until the % scale reading is 95-100%. Change the
span adjustment on the transmitter until the error
reading is 0%.
Repeat the zero and span adjustments until the % error
readings are within the accuracy required.
Since the Model 320 calculates the % of error at any
pressure input, the adjustments can be quickly made.
After the zero and span adjustments are made, the
linearity can be quickly checked at 25, 50 and 75% of
scale and the error % read out directly.
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