Martel Electronics 235 - Manual (Page 55)

desired simulated temperature. The display readout will reflect the
actual temperature being simulated at the terminals as the calibrator
adjusts its output to compensate for errors and drift. When the display
indicates the selected temperature, the output is properly set to
simulate the requested RTD.
The RTD simulation requires that the unit under test supply a nominal
.1 to 2 milliamp test current. Pulsing excitation requires a minimum 60
mSecond pulse width, at 1 Hertz minimum, with no overshoot or
ringing. If the calibrator detects that the current is absent or out of
range, it will display OPEN or OVRANGE as appropriate. The polarity of
the current is significant and is the same as the voltage terminals, i.e.,
red is positive. If the test current is of the incorrect polarity, the
calibrator will display REVERSED. Simply reverse the leads at the
calibrator or the devise under test.
The top line of the display contains information about the
measurements being made. The first three characters indicate that
RTD is selected. Next is the temperature scale.
Output Functions
230/235 50
RTD °F
+ 212.0