TM Page 8
3.1.1
TX31D/1/IFM Input Connections & Scaling
Input sensitivity of the transmitter input is set by a resistor (Rg), which is soldered across pins P6 and P7. This sets the
gain of the input amplifier such that its output at (at full scale signal input) uses
±
41.5% of the total A/D convertor range.
The remaining
±
8.5% allows signal source offsets of up to
±
20% of full scale to be within the dynamic range of the system
and thus removable at the demodulator/decoder unit (via the zero control).
From 1/1/2006 all transmitters have VEx increased from 4.096V to 5VDC. As the A/D converter uses VEx as a reference,
the input sensitivity equation is slightly altered. Equation for both version are listed below:
Transmitters with+ 4.096VEx
Rg is calculated from:
Alternatively:
Full Scale mV In is the mV output from the strain gauge bridge, transducer or other signal source.
In the case of a four arm fully active torsion bridge, the mV output for a given strain may be calculated from:
E
=
Strain in Microstrains
G.F.
=
Gauge Factor
4.096
=
Bridge Excitation Voltage
Transmitters are usually shipped with Rg=100 ohms, giving a full scale input sensitivity of;
Transmitters with+5.0VEx
Rg is calculated from:
Alternatively:
Full Scale mV In is the mV output from the strain gauge bridge, transducer or other signal source.
In the case of a four arm fully active torsion bridge, the mV output for a given strain may be calculated from:
E
=
Strain in Microstrains
G.F.
=
Gauge Factor
4.096
=
Bridge Excitation Voltage
Transmitters are usually shipped with Rg=100 ohms, giving a full scale input sensitivity of;
50,000 x Required Full Scale mV In
1,700 - Required Full Scale mV In
Rg (ohms) =
1,700 x Rg
50,000 + Rg
Full Scale Range in mV =
mV = E x G.F. x 4.096
1,000
1,700 x 100
50,000 + 100
Full Scale Range in mV =
= ±3.393mV
50,000 x Required Full Scale mV In
2,075.2 - Required Full Scale mV In
Rg (ohms) =
2,075.2 x Rg
50,000 + Rg
Full Scale Range in mV =
mV = =
E x G.F. x 5
1,000
2,075.2 x 100
50,000 + 100
Full Scale Range in mV =
= ±4.142mV
Summary of Contents for TX31D/1/IFM
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