Programming Using Hand-Held Terminal
3.7
The sensor typical curve may be scheduled on the TT301 EEPROM memory as a 16-point table. These
tables are usually supplied by the sensor manufacturer, but may also be obtained at a lab test.
The special sensor function may not be used when the setpoint generating function is being used and
vice-versa.
The options for configuring the special sensor are:
Range – For the Ohm sensor there are 3 ranges: 0 to 100, 0 to 400 and 0 to 2000 ohm. For the mV
sensor there are also 3 ranges: -6 to 22, -10 to 100 and –50 to 500.
Connection – There are 4 options: differential, two wires, three wires and four wires.
X and Y Tables – The special sensor table points are inserted here. The sensor input is stored as an
X-variable. The chosen output is stored as a Y-variable (19999 ≤ Y ≤ +19999). The X-input should
always have growing values.
X = Ohm or mV terminal block input.
Y = Chosen output in engineering units.
Watch the following limitations for the X variable values:
DIFFERENTIAL (each input)
Table 3.2 – Special Sensor Input Range
V.INF Calibration range lower limit. The least possible value for transmitter calibration when using this
special sensor.
V.SUP Calibration range upper limit. The most possible value for transmitter calibration when using this
special sensor.
Minimum Span The least possible span for transmitter calibration when using this special sensor.
Unit – Engineering Unit to be associated to the measured variable. If one from most of 100 units is
selected, the respective HART protocol code will be attributed to this parameter. This way, the whole
supervisory system having HART protocol may access the Unit menu.
PID
This option adjusts the PID parameters including the Setpoint, change on auto/manual mode and the
tuning parameters.
The TT301 with an activated PID works as a controller/transmitter, while, deactivated, it works only as a
transmitter
The transmitter 4/20mA output may become a PID controller output, following the equation below:
Where:
e = PV – SP (Direct) or SP – PV (Reverse)
SP = Setpoint
PV = Process Variable
Kp = Proportional Gain
Td = Derivative Time
MV = Output
Tr = Integration Time
See below a list of configurations feasible on the PID function.
PID Controller – ON/OFF
Tuning Parameters – This feature configures the Kp, Tr and Td tuning parameters, as well as
output limits and rate.
dt
dPV
Tdedt
Tr
eKpMV .
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