Campbell A5B40 User Guide

MODEL A5B40

MILLIVOLT-LEVEL ISOLATION AMPLIFIER WITH FILTER

OPERATING INSTRUCTIONS

1. GENERAL

Campbell Scientific's Model A5B40 Isolation
Amplifier is a peripheral that provides electrical
isolation for the analog inputs of CSI
dataloggers. The A5B40 is designed around
the Analog Devices model 5B40-03 Millivolt
Input Module. A fourth-order, low-pass filter,
with a 50 Hz cutoff frequency, was added to
reject noise while maintaining measurement
rates of up to 10 samples per second.

The A5B40 is powered by the datalogger's 12
volt output, (automatically switched to conserve
power), and isolates one differential analog
input. In most applications, a single A5B40 is
used between an AM32 Multiplexer and the
datalogger, thus providing isolation for up to 32
analog channels with a single amplifier.

When measuring thermocouples, the model
A5B40 requires special datalogger PROMs.
These PROMs contain special instructions used
to linearize the thermocouple signals and
compensate for the reference junction
temperature.

3. PHYSICAL CONNECTIONS

Connections to the datalogger for the A5B40
are as follows:

A5B40 Datalogger

IN HI Sensor HI or Mux Com HI

IN LO Sensor LO or Mux Com LO

+12V 12V

GND GND

OUT HI Analog Channel HI

OUT LO Analog Channel LO

ENABLE Control Port or Excitation Ch.

4. MAKING MEASUREMENTS

The maximum and minimum signal inputs to the
A5B40 are +100 mV and -100 mV respectively.
The A5B40 applies a gain of 50 to these signal
and outputs them to the datalogger as +5 V and

-5 V respectively.
The control port connected to the enable

terminal must be switched on prior to the
Instruction making the measurement.

2. PROM INSTALLATION

21X(L): To install OSXA5-0.1, OSXA5-1.1, or
OSXA5-2.1 operating system software, simply
follow the instructions as outlined in the
attached document entitled "Installation of 21X
Micrologger OSX PROM Update" substituting
the following PROM assignments in Instruction
4:

Location PROM Signature

8 6704 24486

7 6705 42295
OSXA5-0.1: 6 6706 13044
OSXA5-1.1: 6 6707 33417
OSXA5-2.1: 6 6708 6820

NOTE:

Item No on each individual PROM.

PROM numbers are labeled as

Measuring Millivolt Signals -

instruction that you would normally use to
measure the signal but remember to use an
input range of 5000 mV and to apply a multiplier
of 0.02 to convert to the true mV signal.

Measuring Thermocouples -

14 as usual, but be sure to insert the digit "8" in
front of the thermocouple type code. For
example, to measure a type T thermocouple,
enter "81" for the type code (Parameter 4).
With the preceding 8 in the code, the datalogger
will automatically apply the multiplier of 0.02 to
the signal before converting to degrees C.

Use the same

Use Instruction

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