Campbell AM16/32B User manual

Table of Contents – i
AM16/32B
Relay Multiplexer
Revision: 12/20
Copyright © 1987 – 2020
Campbell Scientific, Inc.

Table of Contents – ii
Table of contents
1. Introduction ....................................................................................................................................................1
1.1 Typical applications .....................................................................................................................................1
1.2 Compatibility..................................................................................................................................................1
2. Precautions..................................................................................................................................................... 2
3. Initial inspection ............................................................................................................................................ 2
4. QuickStart....................................................................................................................................................... 3
5. Overview......................................................................................................................................................... 9
6. AM16/32B specifications ............................................................................................................................10
7. Installation .....................................................................................................................................................12
7.1 Wiring to data logger ...............................................................................................................................13
7.1.1 Control terminals..................................................................................................................................13
7.1.2 COM terminals ......................................................................................................................................13
7.1.3 Measurement terminals .....................................................................................................................14
7.2 Grounding ....................................................................................................................................................14
7.3 Power supply ...............................................................................................................................................14
7.4 Installation in enclosure............................................................................................................................15
8. Operation ......................................................................................................................................................15
8.1 Programming...............................................................................................................................................16
8.1.1 Short Cut programs .............................................................................................................................16
8.1.2 Using CRBasic MuxSelect() instruction ..........................................................................................18
8.1.3 General programming considerations...........................................................................................18
8.1.4 Mixed sensor types..............................................................................................................................19
8.2 General measurement considerations.................................................................................................19
8.2.1 Long cable lengths ..............................................................................................................................19
8.2.2 Completion resistors ...........................................................................................................................19
8.2.3 Contact degradation ...........................................................................................................................19
Appendix A. Importing Short Cut code into CRBasic Editor ....................................................................20
Appendix B. Example measurements and programs ................................................................................21
B.1 Single-ended voltage measurement....................................................................................................21
B.2 Differential voltage measurement .......................................................................................................23
B.3 Half-bridge measurement ......................................................................................................................24
B.4 Full-bridge measurement .......................................................................................................................25
B.5 CS616 measurement.................................................................................................................................26

Table of Contents – iii
Appendix C. Thermocouple measurement .................................................................................................28
C.1 Measurement considerations ................................................................................................................28
C.1.1 Reference junction ..............................................................................................................................28
C.1.2 Data logger reference........................................................................................................................28
C.1.3 AM16/32B reference...........................................................................................................................30
C.1.4 Thermal gradients ...............................................................................................................................30
List of Figures
FIGURE 5-1. AM16/32B Relay Multiplexer............................................................................................................10
FIGURE 7-1. Example of AM16/32B-to-data-logger signal connection (4x16 mode) ............................14
FIGURE B-1. Typical single-ended voltage measurement connection ......................................................22
FIGURE B-2. Typical differential voltage measurement connection...........................................................23
FIGURE B-3. Typical half-bridge measurement connection .........................................................................24
FIGURE B-4. Full-bridge measurement ...............................................................................................................26
FIGURE C-1. Differential thermocouple measurement with reference junction at the data logger.29
FIGURE C-2. Differential thermocouple measurement with reference junction at the AM16/32B
(using 107-L thermistor) ...........................................................................................................................................29
FIGURE C-3. AM16/32B aluminum cover plate.................................................................................................30
List of Tables
Table 7-1. Control terminal function and data logger connection1.............................................................13
Table B-1. Wiring for single-ended voltage measurements CRBasic example .......................................22
Table B-2. Wiring for differential voltage measurements CRBasic example ...........................................23
Table B-3. Wiring for Campbell Scientific 107 temperature sensors CRBasic example........................25
Table B-4. Wiring for Load Cells CRBasic Example .........................................................................................26
Table B-5. Wiring for CS616 Sensor CRBasic Example ................................................................................... 27

AM16/32B Relay Multiplexer 1
1. Introduction
The primary function of the AM16/32B multiplexer (also known as a mux) is to increase the
number of sensors that can be measured by CR6, CR3000, CR1000X, CR800-series, CR300-series,
and CR1000 data loggers. The AM16/32B is positioned between the sensors and the data logger.
Mechanical relays in the AM16/32B connect each of the sensor channels in turn to a common
output destined for the data logger. The user program advances the multiplexer through the
sensor channels, making measurements and storing data.
A slide switch located on the AM16/32B top panel selects one of two modes of operation. In 2x32
mode, the multiplexer adds 32 terminal pairs. In 4x16 mode, it adds 16 terminal groups with four
terminals each. The data logger program is written according to the selected mode and the
sensors to be measured.
The maximum number of sensors multiplexed by an AM16/32B depends primarily on the type(s)
of sensors to be measured.
NOTE:
This manual provides information for CRBasic data loggers and AM16/32Bs with serial numbers
greater than 5056.
For Edlog and other retired data logger support, or for specifications for AM16/32Bs with serial
numbers less than 5056, see an older version of this manual at www.campbellsci.com/old-
manuals.
1.1 Typical applications
The AM16/32B is intended for use in applications where more terminals are needed than the data
logger has available. Most commonly, the AM16/32B is used to multiplex analog sensor signals,
although it can also be used to multiplex switched excitations, continuous analog outputs, or even
certain pulse counting measurements (those that require only intermittent sampling). It is also
possible to multiplex sensors of different, but compatible, types (see Mixed sensor types (p. 19)).
1.2 Compatibility
The AM16/32B is compatible with Campbell Scientific CR6, CR3000, CR1000X, CR800-series,
CR300-series, and CR1000 data loggers.
The AM16/32B is compatible with a wide variety of commercially available sensors. As long as
relay contact current maximums are not exceeded (see Precautions (p. 2)), and no more than four

AM16/32B Relay Multiplexer 2
lines are switched at a time, system compatibility for a specific sensor is determined by sensor-
data logger compatibility.
NOTE:
The AM16/32B is also compatible with the CDM-A108 and CDM-A116 24-bit analog input
modules by using the CRBasic CDM_MuxSelect() instruction. Refer to the
CRBasic Help
for
information on using the AM16/32B with these modules. The CDM-A100 Series manual includes
a sample program for the CDM-A108 and the AM16/32B.
2. Precautions
The AM16/32B is not designed to multiplex power. Its intended function is to switch low-level
analog signals. Switched currents in excess of 30 mA will degrade the relay contacts involved,
rendering that channel unsuitable for further low-level analog measurement. Customers who
need to switch power are directed to Campbell Scientific SDM-CD16AC, A6REL-12, or A21REL-12
relays.
Changing the setting of the mode switch from 4x16 to 2x32 connects COM ODD H to
COM EVEN H and also COM ODD L to COM EVEN L. After wiring the AM16/32B, exercise due
care to avoid inadvertently putting excess voltage on a line or short-circuiting a power supply,
which might damage connected devices such as data logger, wiring panel, sensor, or multiplexer,
and which would not be covered under warranty.
3. Initial inspection
•The AM16/32B ships with:
o4 grommets
o4 screws
•Upon receipt of the AM16/32B, inspect the packaging and contents for damage. File
damage claims with the shipping company.
•Immediately check package contents. Thoroughly check all packaging material for product
that may be concealed. Check model number, part numbers, and product descriptions
against the shipping documents. Model or part numbers are found on each product. On
cables, the number is often found at the end of the cable that connects to the
measurement device. Ensure that the expected lengths of cables were received. Contact
Campbell Scientific immediately if there are any discrepancies.

AM16/32B Relay Multiplexer 3
4. QuickStart
Short Cut is an easy way to program the data logger to make measurements through an
AM16/32B multiplexer. Short Cut is included in installations of LoggerNet , PC400 , PC200W , and
RTDAQ . It is also available as a download on www.campbellsci.com. Short Cut supports the CR6,
CR3000, CR1000X, CR800-series, and CR1000 data loggers when creating a program to take
measurements through an AM16/32B. Short Cut does not include support for programming the
CR300-series to use the AM16/32B. To use the AM16/32B with the CR300 series, the program
must be created in the CRBasic Editor . See Single-ended voltage measurement (p. 21) and
Differential voltage measurement (p. 23) for CR300-series programming examples.
This section will demonstrate programming a data logger to measure 6 Campbell Scientific 107
temperature sensors as an example for creating a program using a multiplexer. With minor
changes, these steps also apply to other measurements and data loggers.
Open
Short Cut
. From the
LoggerNet
toolbar, click
Program
>
Short
Cut
. In
PC200W
and
PC400
,
click on the
Short Cut
icon.
Select
Create
New
Program
.

AM16/32B Relay Multiplexer 4
NOTE:
The first time
Short Cut
is
run, a prompt will appear asking
for a choice of first notch
frequency. Select
60 Hz Noise
Rejection
for the United States and
areas using 60 Hz AC voltage.
Select
50 Hz Noise Rejection
for
most of Europe and areas that
operate at 50 Hz.
A second prompt lists sensor
support options.
Campbell
Scientific,
Inc. (US)
is the best
option outside Europe.
To change the first notch
frequency or sensor support
option for future programs, use the
Program
menu.

AM16/32B Relay Multiplexer 5
Select the data logger model in the
Datalogger Model
drop-down list.
This tutorial uses the CR6-series
data logger.
The
Progress Bar
is used to track
the progress of the program being
created. It is also used to jump
directly to any step in the
programming process.
The next window displays
Available
Sensors and Devices
. Expand a
folder by clicking on the symbol.
Expand the
Devices
folder, then
double-click on the
AM16/32
to
add it to the
Selected
panel.

AM16/32B Relay Multiplexer 6
When the AM16/32 multiplexer is
added as a device, a new
AM16/32
tab will appear at the bottom of
the
Available
Sensors
and
Devices
pane. With the
AM16/32
tab
selected, select the
Sensors
>
Temperature
subfolder.
Doubleclick on
107 Temperature
Probe (4-wire)
.
In the resulting window, enter the
number of 107 temperature probes
to measure on this AM16/32B
multiplexer. For this tutorial, enter
6
as the number of 107 (4-wire)
sensors to add. Click
OK
in the
dialog window to accept the
default name of
T107_C
and the
default units of
Deg C
.

AM16/32B Relay Multiplexer 7
In the
Scan
Interval
box, enter how
frequently the data logger should
make measurements. When
measuring with an AM16/32B
multiplexer, an interval of 30
seconds or longer is
recommended. Enter
30
and select
Seconds
.
Click
Next
.
After adding the measurements,
click
Wiring Diagram
to see how
the sensors are wired to the
AM16/32B and how the AM16/32B
is wired to the data logger. The
data logger tab (
CR6 Series
in this
example) shows the connection
between the AM16/32B and the
data logger, and the
AM16/32
tab
shows the sensor connection to
the AM16/32B.