DI-500/510 Series and DI-750/760 Series Hardware Manual
5B Modules
28
DI-5B34 Linearized 2- or 3-Wire RTD Input Modules
DESCRIPTION
Each DI-5B34 RTD input module provides a single channel of RTD input which is filtered, isolated, amplified, lin-
earized, and converted to a high level analog voltage output (see block diagram). This voltage output is logic switch
controlled, which allows these modules to share a common analog bus without the requirement of external multiplex-
ers.
The DI-5B modules are designed with a completely isolated computer side circuit which can be floated to ±50V from
Power Common, pin 16. This complete isolation means that no connection is required between I/O Common and
Power Common for proper operation of the output switch. If desired, the output switch can be turned on continuously
by simply connecting pin 22, the Read-Enable pin to I/O Common, pin 19.
RTD excitation is provided from the module by two matched current sources. When using a three-wire RTD, this
method allows an equal current to flow in each RTD lead, which cancels the effects of lead resistances. The excitation
currents are very small (0.25mA for 100W Pt and 120W Ni, and 1.0mA for 10W Cu) which minimizes self-heating of
the RTD.
Signal filtering is accomplished with a six-pole filter which provides 95dB of normal-mode-rejection at 60Hz and
90dB at 50Hz. Two poles of this filter are on the field side of the isolation barrier, and the other four are on the com-
puter side. After the initial field-side filtering, the input signal is chopped by a proprietary chopper circuit. Isolation is
provided by transformer coupling, again using a proprietary technique to suppress transmission of common mode
spikes or surges. The module is powered from +5VDC, ±5%.
A special input circuit on the DI-5B34 modules provides protection against accidental connection of power-line volt-
ages up to 240VAC.
Ordering Information
MODEL
INPUT RANGE
OUTPUT RANGE
ACCURACY*
100
Ω
Pt,
α
= 0.00385
DI-5B34-01
DI-5B34-02
DI-5B34-03
DI-5B34-04
-100°C (-148°F) to +100°C (+212°F)
0°C (32°F) to +100°C (+212°F)
0°C (32°F) to +200°C (+392°F)
0°C (32°F) to +600°C (+1112°F)
0V to +5V
0V to +5V
0V to +5V
0V to +5V
±0.46°C
±0.36°C
±0.46°C
±0.88°C
4
6
5
3
1
2
3
4
+EXC
+In
-In
-EXC
Termination
Block
Surge
Suppression
and
Protection
LPF
1
2
NC
NC
Amplifier
Isolated
Computer-Side
Power
+V
-V
LPF
20
19
22
V out
I/O Common
RD EN\
Isolated
Field-Side
Power
+V
-V
17
+5V
16
Power Common
•
Power
Oscillator
•
•
RTD
NC
2 Wire
3 and 4 Wire
(1)
4 Wire
(1)
Linearizer
•
-V
+V
•
NOTE: (1) 4-wire sensors may
be used with this module.
However, for true 4-wire
measurement, use DI-5B35
Free Datasheet http://www.datasheet4u.com/
