Campbell AM16/32B Instruction Manual

INSTRUCTION MANUAL

AM16/32B Relay Multiplexer

Copyright © 1987- 2016

Campbell Scientific, Inc.

Revision: 7/16

Guarantee







This equipment is guaranteed against defects in materials and workmanship.
We will repair or replace products which prove to be defective during the
guarantee period as detailed on your invoice, provided they are returned to us
prepaid. The guarantee will not apply to:

Equipment which has been modified or altered in any way without the

written permission of Campbell Scientific
Batteries
Any product which has been subjected to misuse, neglect, acts of God or

damage in transit.

Campbell Scientific will return guaranteed equipment by surface carrier
prepaid. Campbell Scientific will not reimburse the claimant for costs incurred

in removing and/or reinstalling equipment. This guarantee and the Company’s

obligation thereunder is in lieu of all other guarantees, expressed or implied,
including those of suitability and fitness for a particular purpose. Campbell
Scientific is not liable for consequential damage.

Please inform us before returning equipment and obtain a Repair Reference
Number whether the repair is under guarantee or not. Please state the faults as
clearly as possible, and if the product is out of the guarantee period it should
be accompanied by a purchase order. Quotations for repairs can be given on
request. It is the policy of Campbell Scientific to protect the health of its
employees and provide a safe working environment, in support of this policy a

“Declaration of Hazardous Material and Decontamination” form will be

issued for completion.

When returning equipment, the Repair Reference Number must be clearly
marked on the outside of the package. Complete the “Declaration of
Hazardous Material and Decontamination” form and ensure a completed copy
is returned with your goods. Please note your Repair may not be processed if
you do not include a copy of this form and Campbell Scientific Ltd reserves
the right to return goods at the customers’ expense.

Note that goods sent air freight are subject to Customs clearance fees which
Campbell Scientific will charge to customers. In many cases, these charges are
greater than the cost of the repair.

Campbell Scientific Ltd,

80 Hathern Road,

Shepshed, Loughborough, LE12 9GX, UK

Tel: [phone]

Fax: [phone]

Email: [e-mail]

www.campbellsci.co.uk

PLEASE READ FIRST

About this manual

Please note that this manual was originally produced by Campbell Scientific Inc. primarily for the North
American market. Some spellings, weights and measures may reflect this origin.

Some useful conversion factors:

Area: 1 in2 (square inch) = 645 mm2

Length: 1 in. (inch) = 25.4 mm

1 ft (foot) = 304.8 mm
1 yard = 0.914 m
1 mile = 1.609 km

In addition, while most of the information in the manual is correct for all countries, certain information
is specific to the North American market and so may not be applicable to European users.

Differences include the U.S standard external power supply details where some information (for
example the AC transformer input voltage) will not be applicable for British/European use. Please note,

however, that when a power supply adapter is ordered it will be suitable for use in your country.

Reference to some radio transmitters, digital cell phones and aerials may also not be applicable
according to your locality.

Some brackets, shields and enclosure options, including wiring, are not sold as standard items in the
European market; in some cases alternatives are offered. Details of the alternatives will be covered in
separate manuals.

Part numbers prefixed with a “#” symbol are special order parts for use with non-EU variants or for
special installations. Please quote the full part number with the # when ordering.

Mass: 1 oz. (ounce) = 28.35 g
1 lb (pound weight) = 0.454 kg

Pressure: 1 psi (lb/in2) = 68.95 mb

Volume: 1 UK pint = 568.3 ml

1 UK gallon = 4.546 litres
1 US gallon = 3.785 litres

Recycling information

At the end of this product’s life it should not be put in commercial or domestic refuse but
sent for recycling. Any batteries contained within the product or used during the
products life should be removed from the product and also be sent to an appropriate
recycling facility.

Campbell Scientific Ltd can advise on the recycling of the equipment and in some cases
arrange collection and the correct disposal of it, although charges may apply for some
items or territories.

For further advice or support, please contact Campbell Scientific Ltd, or your local agent.

Campbell Scientific Ltd, 80 Hathern Road, Shepshed, Loughborough, LE12 9GX, UK

Tel: [phone] Fax: [phone]

Email: [e-mail]

www.campbellsci.co.uk

Precautions

DANGER — MANY HAZARD S ARE ASSOCIATED WITH INSTALLING, USING, M AINTAINING, AND WORKING ON
OR AROUND TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS,
CROSSARMS, ENCLOSURES, ANTENNAS, ETC. FAILURE TO PROPERLY AND COM P LE TE LY ASS E M BLE ,
INSTALL, OPERATE, USE, AND MAINTAIN TRIPODS, TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED
WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS INJURY, PROPERTY DAMAGE, AND
PRODUCT FAILURE. TAKE ALL REASONABLE PRECAUTIONS TO AVOID THESE HAZARDS. CHECK WITH YOUR
ORGANIZATION'S SAFETY COORDINATOR (OR POLICY) FOR PROCEDURES AND REQUIRED PROTECTIVE
EQUIPMENT PRIOR TO PERFORMING ANY WORK.

Use tripods, towers, and attachments to tripods and towers only for purposes for which they are designed. Do not
exceed design limits. Be familiar and comply with all instructions provided in product manuals. Manuals are
available at www.campbellsci.eu or by telephoning [phone] (UK). You are responsible for conformance
with governing codes and regulati ons, including safety regulati ons, and the integrity and locati on of structures or land
to which towers, tripods, and any attachments are attached. Installation sites should be evaluated and approved by a
qualified engineer. If questions or co ncerns arise regarding installation, use, or maintenance of tripods, towers,
attachments, or electrical connections, consult with a licensed and qualified engineer or electrician.

General

• Prior to performing site or installation work, obtain required approvals and permits. Comply with all

governing structure-height regulations, such as those of the FAA in the USA.

• Use only qualified personnel for installation, use, and maintenance of tripods and towers, and any

attachments to tripods and towers. The use of licensed and qualified contractors is highly recommended.

• Read all applicable instructions carefully and understand procedures thoroughly before beginning work.

• Wear a hardhat and eye protection, and take other appropriate safety precautions while working on or

around tripods and towers.

• Do not climb tripods or towers at any time, and prohibit climbing by other persons. Take reasonable

precautions to secure tripod and tower sites from trespassers.

• Use only manufacturer recommended parts, materials, and tools.

Utility and Electrical

• You can be killed or sustain serious bodily injury if the tripod, tower, or attachments you are installing,

constructing, using, or maintaining, or a tool, stake, or anchor, come in contact with overhead or
underground utility lines.

• Maintain a distance of at least one-and-one-half times structure height, or 20 feet, or the distance

required by applicable law, whichever is greater, between overhead utility lines and the structure (tripod,
tower, attachments, or tools).

• Prior to performing site or installation work, inform all utility companies and have all underground utilities

marked.

• Comply with all electrical codes. Electrical equipment and related grounding devices should be installed

by a licensed and qualified electrician.

Elevated Work and Weather

• Exercise extreme caution when performing elevated work.

• Use appropriate equipment and safety practices.

• During installation and maintenance, keep tower and tripod sites clear of un-trained or non-essential

personnel. Take precautions to prevent elevated tools and objects from dropping.

• Do not perform any work in inclement weather, including wind, rain, snow, lightning, etc.

Maintenance

• Periodically (at least yearly) check for wear and damage, including corrosion, stress cracks, frayed cables,

loose cable clamps, cable tightness, etc. and take necessary corrective actions.

• Periodically (at least yearly) check electrical ground connections.

WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL
SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER
INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS
SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC.

Table of Contents

PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.

1. Introduction ................................................................ 1

1.1 Typical Applications ............................................................................ 1

1.2 Compatibility ....................................................................................... 1

2. Precautions ................................................................ 2

3. Initial Inspection ......................................................... 2

4. QuickStart ................................................................... 2

5. Overview ..................................................................... 5

6. AM16/32B Specifications ........................................... 6

7. Installation .................................................................. 8

7.1 Wiring to Datalogger ........................................................................... 8

7.1.1 Control Terminals ......................................................................... 8

7.1.2 COM Terminals ............................................................................ 8

7.1.3 Measurement Terminals ................................................................ 9

7.2 Grounding ............................................................................................ 9

7.3 Power Supply ....................................................................................... 9

7.4 Installation in Enclosure ..................................................................... 10

8. Operation .................................................................. 10

8.1 Programming ...................................................................................... 11

8.1.1 General Programming Considerations ........................................ 12

8.1.2 Mixed Sensor Types ................................................................... 12

8.2 General Measurement Considerations ............................................... 13

8.2.1 Long Cable Lengths .................................................................... 13

8.2.2 Earth Ground............................................................................... 13

8.2.3 Completion Resistors .................................................................. 13

8.2.4 Contact Degradation ................................................................... 13

Appendices

A. Importing Short Cut Code Into CRBasic Editor ... A-1

B. Example Measurements and Programs ................ B-1

B.1 Single-Ended Voltage Measurement ................................................ B-1

B.2 Differential Voltage Measurement ................................................... B-3

B.3 Half-Bridge Measurement ................................................................ B-4

B.4 Full-Bridge Measurement ................................................................ B-6

i

Table of Contents

CR5000 Program Example ............................................................ B-10

B.5

C. Thermocouple Measurement ................................. C-1

C.1 Measurement Considerations .......................................................... C-1

C.1.1 Reference Junction ................................................................... C-1

C.1.2 Datalogger Reference ............................................................... C-1

C.1.3 AM16/32B Reference .............................................................. C-2

C.1.4 Thermal Gradients .................................................................... C-2

Figures

5-1. AM16/32B Relay Multiplexer ............................................................. 6

7-1. Example of AM16/32B-to-datalogger signal connection (4x16

mode) ............................................................................................... 9

B-1. Typical single-ended voltage measurement connection .................. B-1

B-2. Typical differential voltage measurement connection ..................... B-3

B-3. Typical half-bridge measurement connection ................................. B-5

B-4. Full-bridge measurement ................................................................. B-6

C-1. Differential thermocouple measurement with reference junction

at the datalogger ........................................................................... C-2

C-2. Differential thermocouple measurement with reference junction

at the AM16/32B (using 107-L thermistor) ................................. C-2

C-3. AM16/32B aluminum cover plate ................................................... C-3

Tables

7-1. Control Terminal Function and Datalogger Connection ..................... 8

B-1. Wiring for Single-Ended Voltage Measurements CRBasic

Example ....................................................................................... B-2

B-2. Wiring for Differential Voltage Measurements CRBasic

Example ....................................................................................... B-3

B-3. Wiring for Campbell Scientific 107 Temperature Sensors

CRBasic Example ........................................................................ B-5

B-4. Wiring for Load Cells CRBasic Example ....................................... B-7

B-5. Wiring for CS616 Sensor CRBasic Example .................................. B-9

B-6. Wiring for CR5000 Program Example .......................................... B-10

CRBasic Examples

B-1. Single-Ended Voltage Measurements ............................................. B-2

B-2. Differential Voltage Measurements ................................................ B-4

B-3. Campbell Scientific 107 Temperature Sensors ............................... B-5

B-4. Load Cells ....................................................................................... B-7

B-5. CS616 Sensors................................................................................. B-9

B-6. CR5000 Program Example ............................................................ B-11

ii

NOTE

AM16/32B Relay Multiplexer

1. Introduction

The primary function of the AM16/32B multiplexer is to increase the number
of sensors that can be measured by CR6-series, CR800-series, CR1000,
CR3000, and CR5000 dataloggers. The AM16/32B is positioned between the
sensors and the datalogger. Mechanical relays in the AM16/32B connect each
of the sensor channels in turn to a common output destined for the datalogger.
The user program advances the multiplexer through the sensor channels,
making measurements and storing data.

A slide switch located on the AM16/32B’s 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 datalogger
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.

This manual provides information for CRBasic dataloggers and
serial numbers greater than 5056. The AM16/32B is also
compatible with most of our retired Edlog dataloggers.

For Edlog datalogger support or for specifications on serial
numbers lower 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 datalogger 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
Section 8.1.2, Mixed Sensor Types

1.2 Compatibility

The AM16/32B is compatible with Campbell Scientific’s CR6-series, CR800­series, CR1000, CR3000, and CR5000 dataloggers.

The AM16/32B is compatible with a wide variety of commercially available
sensors. As long as relay contact current maximums are not exceeded (see
Section 2, Precautions
time, system compatibility for a specific sensor is determined by sensor­datalogger compatibility.

.

(p. 12)).

(p. 2)), and no more than four lines are switched at a

1

AM16/32B Relay Multiplexer

NOTE

2. Precautions

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.

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’s 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 datalogger, wiring panel, sensor, or multiplexer, and
which would not be covered under warranty.

3. Initial Inspection

• The AM16/32B ships with:

o 4 each pn 6044, Grommet

o 4 each pn 505, Screw

• 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.

4. QuickStart

Short Cut is an easy way to program your datalogger 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 and the ResourceDVD.

2

This section will guide you through programming a datalogger to measure 6
Campbell Scientific 107 temperature sensors as an example for creating a
program using a multiplexer. With minor changes, these steps can apply to
other measurements and dataloggers.

Open Short Cut. From the

LoggerNet toolbar, click Program |

Select your datalogger model in the

datalogger.

In the Scan Interval box, enter how

Enter 30 and select Seconds.

NOTE The first time Short Cut is run, a prompt will appear asking for a choice of first notch

the Program menu.

Short Cut. In PC200W and PC400,
click on the Short Cut icon.

Select New Program.

Datalogger Model drop-down list.
This tutorial uses the CR6-series

frequently the datalogger should
make measurements. When
measuring with an AM16/32B
multiplexer, we recommend an
interval of 30 seconds or longer.

AM16/32B Relay Multiplexer

Click Next.

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

probably the best fit if you are outside Europe.

To change the first notch frequency or sensor support option for future programs, use

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.

3

AM16/32B Relay Multiplexer

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. Double­click 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.

After adding the measurements,
click Wiring Diagram to see how
the sensors are to be wired to the
AM16/32B and how the AM16/32B
is to be wired to the datalogger. The
datalogger tab (CR6 Series in this
example) shows the connection
between the AM16/32B and the
datalogger, and the AM16/32 tab
shows the sensor connection to the
AM16/32B.

With power disconnected, wire the
sensors and devices as shown in the
wiring diagrams. Insert the wires,
taking care to tighten the terminals
on the conductors themselves, not
the insulation.

4

Click on Sensors in the Progress

If LoggerNet, PC200W, PC400, or

datalogger.

After powering on and sending the program to the datalogger, check the output of sensors in the datalogger
support software data display to make sure they are making reasonable measurements.

list to return to the sensor-selection
screen.

Select any other sensors you have in
the Sensors section. Add sensors to
the datalogger by selecting the
datalogger tab (CR6 in this
example). Add sensors to the
multiplexer by selecting the
AM16/32 tab. Finish the remaining
Short Cut steps to complete the
program. The remaining steps are
outlined in Short Cut Help, which is
accessed by clicking on Help |

Short Cut Help | Contents |
Programming Steps.

AM16/32B Relay Multiplexer

RTDAQ is running on your PC and
the PC-to-datalogger connection is
active, you can click Finish in Short
Cut, and you will be prompted to
send the program just created to the

5. Overview

Under datalogger control, the AM16/32B sequentially connects terminal pairs
or groups to datalogger terminals. This effectively expands the number of
terminals available on a datalogger.

FIGURE 5-1 shows the wiring panel of the AM16/32B multiplexer. The group
of four terminals located near the mode switch are dedicated to the connection
of datalogger power and control lines. COM ODD and EVEN terminals on the
other side of the mode switch carry multiplexed signals destined for datalogger
terminals. The remaining terminals on the AM16/32B are for sensor and
sensor-shield connection. All of the inputs of the AM16/32B are protected

5

AM16/32B Relay Multiplexer

against surges with transient suppression. Datalogger-to-AM16/32B cabling
requires a minimum of six and as many as nine individually insulated wires
with shields.

FIGURE 5-1. AM16/32B Relay Multiplexer

6. AM16/32B Specifications

1, 2

Power

Current Drain
Quiescent: < 210 µA

Active: 6 mA typical in 2x32 mode
11 mA typical in 4x16 mode

Reset

Clock

: Unregulated 9.6 to 16 Vdc

1

: A continuous signal between 3.3 Vdc and

1

: On the transition from <1.5 V to >3.3 V, a

8 Vdc holds the AM16/32B in an active state
(where a clock pulse can trigger a channel
advance). A signal voltage < 0.9 Vdc
deactivates the AM16/32B (clock pulse will
not trigger a channel advance; AM16/32B is
also reset).

channel advance is actuated on the leading
edge of the clock signal; clock pulse should be
a minimum of 1 ms wide; maximum voltage is
8 Vdc.

6

Operational Temperature
Standard: –25 to 50 °C
Extended: –55 to 85 °C

Operational Humidity: 0 to 95%, non-condensing

AM16/32B Relay Multiplexer

Dimensions

Length: 23.9 cm (9.4 in)
Width: 10.2 cm (4.0 in)
Depth: 4.6 cm (1.8 in)

Weight: 680 g (1.5 lb) (approx.)

Mounting Tab
Hole Spacing: 1 x 3 x 9 in. Up to 1/8 in or 3 mm diameter

screws.

3

Expandability

(nominal): 4 AM16/32Bs per CR6

2 AM16/32Bs per CR800/CR850
4 AM16/32Bs per CR3000
4 AM16/32Bs per CR5000
4 AM16/32Bs per CR1000

Maximum Cable Length: Depends on sensor and scan rate. In general,

longer lead lengths necessitate longer
measurement delays. Refer to datalogger and
sensor manuals for details.

Maximum
Switching Current

4

: 500 mA

Contact Specifications
Initial Contact Resistance: <0.1 Ω max.

Initial Contact Bounce: <1 ms
Contact Material: Silver Palladium
Wiper to N.O. Contact
Capacitance: 0.5 pF
Typical Low-current
(<30 mA) Life: 5 x 10

7

operations

Relay Switching
Thermal emf: 0.3 µV typical; 0.5 µV maximum
Operate Time: <10 ms over temperature and supply ranges

Break-before-make guaranteed by design.

Relays disengage from previous selected
channel before engaging next channel.

ESD
Air Discharge: complies with IEC61000-4-2, test level 4

(±15 kV)

Contact Discharge: complies with IEC61000-4-2, test level 4

(±8 kV)

Surge: Complies with IEC61000-4-5, test level 3

(±2 kV, 2 ohms coupling impedance)

1

Reset and clock protected by 8 V varistors; +12 V input is protected by +16 V

TransZorb®.

2

For power specifications on serial numbers less than 5056, refer to an older version of

this manual at www.campbellsci.com/old-manuals.

3

Assumes sequential activation of multiplexers and that each datalogger channel is
uniquely dedicated. If the application requires additional multiplexing capability, please
consult Campbell Scientific for application assistance.

7

AM16/32B Relay Multiplexer

TABLE 7-1. Control Terminal Function and Datalogger Connection1

Power

C, U

7. Installation

7.1 Wiring to Datalogger

7.1.1 Control Terminals

4

Switching currents greater than 30 mA (occasional 50 mA current is acceptable) will
degrade the contact surfaces of the mechanical relays and increase their resistance. This
will adversely affect the suitability of these relays to multiplex low voltage signals.
Although a relay used in this manner no longer qualifies for low voltage measurement,
it continues to be useful for switching currents in excess of 30 mA.

If you are programming your datalogger with Short Cut, skip Section 7.1,
Wiring to Datalogger. Short Cut creates a wiring diagram for you. See Section

4, QuickStart

(p. 2), for a Short Cut tutorial.

Removable terminal strips allow wiring to remain intact while the multiplexer
is used elsewhere. The green terminal strips are easily removed; no tools are
required. Replacement terminal strips may be purchased from Campbell
Scientific.

TABLE 7-1 depicts control connections to Campbell Scientific dataloggers.

1

Connect the cable shield to G on the AM16/32B and to G on the CR6 series, CR800

series, CR1000, or CR3000. Connect to ⏚ on the CR5000.

7.1.2 COM Terminals

The four terminals dedicated to multiplexer-datalogger connection are located
under the blue COM label next to the mode switch. The terminals are labeled:

ODD H/L and EVEN H/L. In 4x16 mode, the AM16/32B maintains the four
COM terminals electrically isolated from one another. In 2x32 mode, the

AM16/32B maintains an internal connection between ODD H and EVEN H
and between ODD L and EVEN L. How the COM terminals connect to
datalogger terminals determines the function of the measurement terminals. For
proper function, these terminals must be wired according to the measurement
instructions in the CRBasic program. See Section 8, Operation
and Appendix B, Example Measurements and Programs

Control

Terminal

12V

G

CLK

RES

Function Datalogger Connection Terminal

Power

ground

Clock

Reset

C (control port), U terminal configured for

terminal configured for control

12V

G (power ground)

control

(p. 10), for details

(p. B-1), for examples.

Common

terminals are provided next to the COM ODD and COM EVEN

terminals. They connect internally to the other thirty-two
AM16/32B and are connected at all times (not switched). Their function is to

8

terminals on the

AM16/32B Relay Multiplexer

provide a path to ground for sensor cable shields. A COM
wired to datalogger ground (⏚) as shown in FIGURE 7-1.

FIGURE 7-1. Example of AM16/32B-to-datalogger signal connection

(4x16 mode)

7.1.3 Measurement Terminals

Wire sensors and transducers according to the COM terminal connections and
the measurement instructions in the CRBasic program. See Section 8,

Operation
Programs

(p. 10) for details and Appendix B, Example Measurements and

(p. B-1), for examples.

terminal should be

7.2 Grounding

The AM16/32B has a ground lug that should be connected to earth ground via
an 8 AWG wire. This connection should be as short as possible. The ground
lug provides a path to dissipate surges that might propagate on a sensor’s shield
line. An 8-V, bi-polar TransZorb® connects shield ground to the ground lug.

The AM16/32B G terminal is connected to datalogger power ground. The
AM16/32B G terminal is also connected to the cable shield and, via that, to
datalogger power ground (see TABLE 7-1). If a separate power supply is used,
the AM16/32B ground should also connect to the power supply’s ground. An

AM16/32B COM
via the cable that connects the COM terminals (see FIGURE 7-1). The
datalogger must connect to earth ground by one of the methods described in the
installation and maintenance section of the datalogger operator’s manual.

7.3 Power Supply

The AM16/32B requires a continuous power supply for operation. The positive
side of the power supply is connected to 12V, and the negative side is
connected to G. Connect the G wire first for safety.

The average power required to operate an AM16/32B depends on the
percentage of time it is active per time period. At a minimum, the power supply
must be able to sustain the system between site visits anticipating the worst
environmental extremes. Refer to the application note Power Supplies and the

terminal should connect to a datalogger signal ground (⏚)

9

AM16/32B Relay Multiplexer

NOTE

7.4 Installation in Enclosure

8. Operation

video Power Budgeting , both available at www.campbellsci.com, for more
help in selecting a power supply.

The AM16/32B must be protected from moisture. Moisture in the electronics
will seriously damage the AM16/32B. In most cases, protection from water is
easily accomplished by placing the AM16/32B in a weathertight enclosure with
desiccant and elevating the enclosure above the ground. Desiccant in
enclosures should be changed periodically.

Mount the AM16/32B to an enclosure backplate by inserting the included
screws through the mounting holes in the AM16/32B and into the included
nylon anchors.

The reset (RES) line is used to switch on the AM16/32B by applying 3.3 to 8
Vdc. When this line drops lower than 0.9 Vdc, the multiplexer enters a
quiescent, low current-drain state. In the quiescent state, the common (COM)
terminals are electrically disconnected from all of the sensor input channels.
RES should always connect to a datalogger terminal configured for control.
The PortSet() instruction controls the reset line.

After RES has been set high, a pulse on CLK advances the channels. The
voltage level must fall below 1.5 Vdc and then rise above 3.3 Vdc to clock the
multiplexer. In a typical operation, this is accomplished with either the

PulsePort() or PortSet() instruction. Another method of operation uses the
MuxSelect() instruction to advance to a channel specified in the instruction.

When RES first goes high, the COM terminals (ODD H, ODD L and EVEN
H, EVEN L) are disconnected from all measurement terminals. When the first
CLK pulse arrives, the COM terminals are switched to connect with the first

set of measurement terminals according to the mode switch, either 4x16 or
2x32. When a second CLK pulse arrives, the common lines are switched to
connect to the second set of measurement terminals. The multiplexer advances
a channel on the rising edge of the CLK pulse.

The CLK pulse should be at least 1 ms long. A delay (typically 10
ms or more) is inserted between the beginning of the CLK pulse
and the measurement instruction to ensure sufficient settling time
to relay contacts.

The terminals for sensor attachment are divided into 16 groups (panel switch
set to 4x16) or into 32 groups (panel switch set to 2x32). The groups consist of
four or two Simultaneously Enabled Terminals (SETs). With the panel switch
set to 4X16, the blue channel numbers apply. The SETs are numbered starting
at 1 (1H, 1L, 2H, 2L) and continuing until SET 16 (31H, 31L, 32H, 32L).

10

In 4x16 mode, the odd-numbered terminals (example: 5H, 5L) are relay­switched to the COM ODD terminals while the even terminals (6H, 6L) are
switched to the COM EVEN terminals. When activated by the RES line, as
the AM16/32B receives clock pulses from the datalogger, each SET of four in
turn is switched into contact with the four COM terminals. For example, when

the first clock pulse is received from the datalogger, SET 1, consisting of 1H,

NOTE
NOTE

1L, 2H, and 2L, is connected to COM ODD H, ODD L, EVEN H, and
EVEN L terminals respectively. When the second clock pulse is received, the
first SET is switched out (SET 1 sensor inputs become open circuits), and SET
2 (3H, 3L, 4H, 4L) are connected to the four COM terminals. A given SET

will typically be connected to the common terminals for 10 ms.

With the panel switch set to 2X32, the white channel numbers apply. The SETs
are labeled beginning with 1H, 1L and ending with 32H, 32L. In 2x32 mode
when the AM16/32B selects a given channel, the H terminal is relay-connected
to both COM H terminals, and the L sensor terminal is connected to both
COM L terminals.

8.1 Programming

In most cases, Short Cut is the best way to create or begin datalogger programs
for the AM16/32B multiplexer. See Section 4, QuickStart
tutorial. The details that follow pertain to CRBasic programming. For
measurement and program examples, see Appendix B, Example Measurements
and Programs

To accommodate the AM16/32 and AM16/32A, Short Cut adds a
delay of 150 ms after disabling the multiplexer. This delay is not
required for the AM16/32B and may be deleted to increase the
speed of the program.

AM16/32B Relay Multiplexer

(p. 2), for a Short Cut

(p. B-1).

Campbell Scientific CRBasic dataloggers use three instructions to operate the
multiplexer: 1) the PortSet() instruction enables or disables the multiplexer, 2)
the SubScan()/NextSubScan instruction begins/ends the measurement loop,
and 3) the PulsePort() instruction clocks through the measurement channels.
The CRBasic program must also specifically increment an index variable and
use that variable to determine where each measurement is stored. The
generalized programming sequence follows:

The CR5000 does not support the PulsePort() instruction. Refer
to CRBasic Example B-6, CR5000 Program Example (p. B-11), for
this datalogger.

'Turn AM16/32 Multiplexer on

PortSet(2,1)
Delay(0,150,mSec)

'Reset counter

LCount=1

'Begin measurement loop

SubScan(0,uSec,5) 'measures 5 sets

'Switch to next AM16/32 Multiplexer channel

PulsePort(1,10000)
'Make measurements

'Increment counter according to measurement mode

LCount=LCount+1

NextSubScan

'Turn AM16/32 Multiplexer off

PortSet(2,0)

The SubScan() instruction is used to create a measurement loop for the
multiplexer. The third parameter in the SubScan() instruction, Count, is the

11

AM16/32B Relay Multiplexer

number of sets on the multiplexer that will be used. For example, if the
instruction is SubScan(0,μSec,7) and the multiplexer is in 2x32 mode, the first
seven terminal pairs (numbers in white) on the multiplexer will be used. When
in 4x16 mode, this instruction will use the first seven groups of four (numbers
in blue) on the multiplexer.

It may be desirable to use the repetition parameter, Reps, of the measurement
instructions between SubScan() and NextSubScan. The repetitions parameter
is the number of sensors per instruction that will be measured. See the
examples below:

Example 1

SubScan(0,μSec,7)
PulsePort(1,10000)

VoltDiff(Dest,1,mV5000,1,True,0,250,1.0,0)

NextSubScan

In this example, one measurement is made per VoltDiff() instruction because
the instruction has a repetition parameter of 1 (the second parameter in the
VoltDiff() instruction). With the multiplexer in 2x32 mode, differential voltage
measurements will be made on the first seven 2x32 terminal pairs because the

Count parameter of the SubScan() instruction is 7.

Example 2

SubScan(0,μSec,7)

PulsePort(1,10000)
VoltDiff(Dest,2,mV5000,1,True,0,250,1.0,0)

NextSubScan

With the multiplexer in 4x16 mode, differential voltage measurements will be
made on the first seven 4x16 terminal groups because the Count parameter of
the SubScan() instruction is 7. Two differential sensors are measured per
terminal group because the VoltDiff() instruction has a repetition parameter of

2. Thus, a total of 14 differential voltage measurements will be made (2
measurement per subscan • 7 subscans = 14).

8.1.1 General Programming Considerations

Excitation voltage, integration time, and delay time associated with measuring
the signal, and the speed at which the channels are advanced, can be varied
within the datalogger program. In general, longer delay times are necessary
when sensors and datalogger are separated by longer lead lengths. Consult the
datalogger or sensor manual for additional information on these topics.

8.1.2 Mixed Sensor Types

In applications where sensor types are mixed, experienced programmers can
create multiple configurations and programming, though it is preferred to use
multiple multiplexers for these situations. When programming for mixed
sensors on a single AM16/32B, it is especially important to verify that each
measurement is reasonable. Consult Campbell Scientific for application
assistance when it is necessary to multiplex markedly different sensor types in
an application.

12

8.2 General Measurement Considerations

8.2.1 Long Cable Lengths

Longer sensor-to-AM16/32B cables result in greater induced and capacitively
coupled voltages (cross talk) between cable wires. It may also be necessary to
program a delay within the measurement instruction to allow time for lead-wire
capacitances to discharge after advancing a channel, before the measurement is
made. This can be done by increasing the Delay parameter in the PulsePort()
instruction or by adding a Delay() instruction after the PulsePort() instruction.
A delay of 20 ms or more is recommended. Please consult the Theory of
Operation section of the datalogger manual for more information.

8.2.2 Earth Ground

The AM16/32B’s ground lug should be connected to earth ground via an 8
AWG wire. This connection should be as short as possible. The AM16/32B
also connects to earth ground via the datalogger. The lead wire that connects
the datalogger power ground to the AM16/32B power ground (G) establishes
this connection. The installation/maintenance section of the datalogger manual
contains more information on grounding procedures.

8.2.3 Completion Resistors

AM16/32B Relay Multiplexer

In some applications, it is advantageous to place completion resistors at the
AM16/32B terminal strips. Certain sensors specific to the use of multiplexers
are available from Campbell Scientific. Examples include soil moisture probes
and thermistor probes. Please consult Campbell Scientific for ordering and
pricing information.

8.2.4 Contact Degradation

Once excitation in excess of 30 mA has been multiplexed, that channel’s relay
contacts have been rendered unsuitable for further low voltage measurement.
To prevent undue degradation, it is advisable to reserve certain channels for
sensor excitation and employ other channels for sensor signals.

13

AM16/32B Relay Multiplexer

14

NOTE

Appendix A. Importing Short Cut Code Into CRBasic Editor

This tutorial shows:

• How to import a Short Cut program into a program editor for

additional refinement

• How to import a wiring diagram from Short Cut into the comments of

a custom program

Short Cut creates files, which can be imported into CRBasic Editor. Assuming
defaults were used when Short Cut was installed, these files reside in the
C:\campbellsci\SCWin folder:

• .DEF (wiring and memory usage information)

• .CR6 (CR6-series datalogger code)

• .CR8 (CR800-series datalogger code)

• .CR1 (CR1000 datalogger code)

• .CR3 (CR3000 datalogger code)

• .CR5 (CR5000 datalogger code)

Use the following procedure to import Short Cut code and wiring diagram into
CRBasic Editor.

1. Create the Short Cut program following the procedure in Section 4,
QuickStart

file name used when saving the Short Cut program.

2. Open CRBasic Editor.

3. Click File | Open. Assuming the default paths were used when Short Cut
was installed, navigate to C:\CampbellSci\SCWin folder. The file of
interest has the .CR6, .CR8, .CR1, .CR3. or .CR5 extension. Select the file
and click Open.

4. Immediately save the file in a folder different from
C:\Campbellsci\SCWin, or save the file with a different file name.

Once the file is edited with CRBasic Editor, Short Cut can no
longer be used to edit the datalogger program. Change the name
of the program file or move it, or Short Cut may overwrite it next
time it is used.

5. The program can now be edited, saved, and sent to the datalogger.

(p. 2). Finish the program and exit Short Cut. Make note of the

6. Import wiring information to the program by opening the associated .DEF
file in a text editor. Copy and paste the section beginning with heading “­Wiring for CRXXX–” into the CRBasic program, usually at the head of
the file. After pasting, edit the information such that an apostrophe (')
begins each line. This character instructs the datalogger compiler to ignore
the line when compiling.

A-1

Appendix B. Example Measurements and Programs

This section covers sensor-to-AM16/32B connections and AM16/32B-to­datalogger connections. Most programs were created in Short Cut. The
following are examples only and should not be construed as the only way to
make a particular measurement. See the measurement section of the datalogger
manual for more information on basic bridge measurements. Most of the
following examples do not depict datalogger-to-AM16/32B control
connections (Section 7.1.1, Control Terminals
implied and required.

B.1 Single-Ended Voltage Measurement

FIGURE B-1 shows a typical connection for single-ended voltage
measurements. Using this method, a datalogger can make up to 48 single­ended voltage measurements through a multiplexer. See CRBasic Example B-1
and TABLE B-1 for a related program and wiring diagram, or use Short Cut to
create your own.

(p. 8)), but their presence is

FIGURE B-1. Typical single-ended voltage measurement connection

The following example is a CR1000 program. With minor adjustments, this
program can be used with the CR6 series, CR800 series, or CR3000. The
AM16/32B must be in 4x16 mode.

B-1

Appendix B. Example Programs

TABLE B-1. Wiring for Single-Ended Voltage Measurements CRBasic Example

⏚ (

⏚

CRBasic Example B-1. Single-Ended Voltage Measurements

'Declare Variables and Units

VoltSE(SEVolt(LCount),3,mV2500,1,True,0,_60Hz,1,0)

CR1000

Signal

Ground

)

1H COM ODD L

1L COM EVEN H

2H COM EVEN L

12V 12V

G G

C1 CLK

C2 RES

Public BattV
Public PTemp_C
Public LCount
Public SEVolt(48)

Units BattV=Volts
Units PTemp_C=Deg C
Units SEVolt=mV

'Define Data Tables

DataTable(Table1,True,-1)

DataInterval(0,60,Min,10)
Sample(48,SEVolt(),FP2)

EndTable

DataTable(Table2,True,-1)

DataInterval(0,1440,Min,10)
Minimum(1,BattV,FP2,False,False)

EndTable

'Main Program

BeginProg

'Main Scan
Scan(30,Sec,1,0)
'Default CR1000 Datalogger Battery Voltage measurement 'BattV'
Battery(BattV)
'Default CR1000 Datalogger Wiring Panel Temperature measurement 'PTemp_C'
PanelTemp(PTemp_C,_60Hz)
'Turn AM16/32 Multiplexer On
PortSet(2,1)
Delay(0,150,mSec)
LCount=1
SubScan(0,uSec,16)
'Switch to next AM16/32 Multiplexer channel
PulsePort(1,10000)
'Generic Single Ended Voltage measurements 'SEVolt()' on AM16/32 Multiplexer

AM16/32B in 4X16 Mode

Control and COM Terminals Measurement Terminals

COM ODD H

Odd-numbered H terminal Sensor 1, 2, and 3 grounds

Odd-numbered L terminal Sensor 1 signal

Even-numbered H terminal Sensor 2 signal

Even-numbered L terminal Sensor 3 signal

COM

Sensors

Sensor 1, 2, and 3 shields

B-2

Appendix B. Example Programs

LCount=LCount+3

EndProg

TABLE B-2. Wiring for Differential Voltage Measurements CRBasic Example

⏚ (

NextSubScan
'Turn AM16/32 Multiplexer Off
PortSet(2,0)
'Call Data Tables and Store Data
CallTable Table1
CallTable Table2
NextScan

B.2 Differential Voltage Measurement

FIGURE B-2 shows a typical connection for differential voltage
measurements. Using this method, a datalogger can make up to 32 differential
voltage measurements through a multiplexer. See CRBasic Example B-2 and
TABLE B-2 for a related program and wiring diagram, or use Short Cut to
create your own.

FIGURE B-2. Typical differential voltage measurement connection

The following example is a CR1000 program. With minor adjustments, this
program can be used with the CR6 series, CR800 series, or CR3000. The
AM16/32B must be in 2x32 mode.

Notice this program uses arrays for multipliers and offsets. This allows you to
adjust multipliers and offsets for each sensor individually. For example, in this
program the fifth multiplier, 8, and the fifth offset, 4, would be applied to the
fifth measurement, DiffV(5).

AM16/32B in 2X32 Mode

CR1000

Control and COM Terminals Measurement Terminals

1H COM ODD H H

1L COM ODD L L

Signal Ground)

COM

12V 12V

Sensors

High signal

Low signal

Shield

G G

C1 CLK

C2 RES

B-3

Appendix B. Example Programs

CRBasic Example B-2. Differential Voltage Measurements

'Declare Variables and Units

EndProg

Public BattV
Public PTemp_C
Public LCount
Public DiffV(32)
Public Mult(32)={9,1,8,8,8,1,5,2,8,5,3,6,2,6,5,5,2,9,1,7,8,8,2,3,9,2,8,1,7,2,7,4}
Public Offs(32)={5,4,9,8,4,1,1,1,7,4,8,2,6,9,7,5,9,2,3,5,2,1,9,3,8,4,3,6,5,9,3,3}

Units BattV=Volts
Units PTemp_C=Deg C
Units DiffV=mV

'Define Data Tables

DataTable(Table1,True,-1)

DataInterval(0,60,Min,10)
Sample(32,DiffV(),FP2)

EndTable

DataTable(Table2,True,-1)

DataInterval(0,1440,Min,10)
Minimum(1,BattV,FP2,False,False)

EndTable

'Main Program

BeginProg

'Main Scan
Scan(30,Sec,1,0)
'Default CR1000 Datalogger Battery Voltage measurement 'BattV'
Battery(BattV)
'Default CR1000 Datalogger Wiring Panel Temperature measurement 'PTemp_C'
PanelTemp(PTemp_C,_60Hz)
'Turn AM16/32 Multiplexer On
PortSet(2,1)
Delay(0,150,mSec)
LCount=1
SubScan(0,uSec,32)
'Switch to next AM16/32 Multiplexer channel
PulsePort(1,10000)
'Generic Differential Voltage measurements 'DiffV()' on AM16/32 Multiplexer
VoltDiff(DiffV(LCount),1,mV2500,1,True,0,_60Hz,Mult(LCount),Offs(LCount))
LCount=LCount+1
NextSubScan
'Turn AM16/32 Multiplexer Off
PortSet(2,0)
'Call Data Tables and Store Data
CallTable Table1
CallTable Table2
NextScan

B.3 Half-Bridge Measurement

FIGURE B-3 shows a typical connection for half-bridge measurements, such
as 107 temperature sensors. Using this method, a datalogger can make up to 48
half-bridge measurements through a multiplexer. See CRBasic Example B-3
and TABLE B-3 for a related program and wiring diagram, or use Short Cut to
create your own.

B-4

Appendix B. Example Programs

TABLE B-3. Wiring for Campbell Scientific 107 Temperature Sensors CRBasic Example

⏚

CRBasic Example B-3. Campbell Scientific 107 Temperature Sensors

'Declare Variables and Units

FIGURE B-3. Typical half-bridge measurement connection

The following example is a CR6-series program. With minor adjustments, this
program can be used with the CR800 series, CR1000, or CR3000. This
program measures 48 Campbell Scientific 107 temperature sensors through an
AM16/32B. The AM16/32B must be in 4x16 mode.

CR6

U3 COM ODD H

U4 COM ODD L

U5 COM EVEN H

U6 COM EVEN L

(Signal

Ground)

12V 12V

G G

U1 CLK

U2 RES

AM16/32B in 4X16 Mode

Control and COM Terminals Measurement Terminals

Odd-numbered H terminal

Odd-numbered L terminal Sensor 1 signal (red wire)

Even-numbered H terminal Sensor 2 signal (red wire)

Even-numbered L terminal Sensor 3 signal (red wire)

COM

Dim LCount
Public BattV
Public PTemp_C
Public T107_C(48)

Units BattV=Volts
Units PTemp_C=Deg C
Units T107_C=Deg C

Sensors

Sensor 1, 2, and 3 excitation

(black wire)

Sensor 1, 2, and 3 grounds and

shields (purple and clear wires)

B-5

Appendix B. Example Programs

'Define Data Tables

EndProg

DataTable(Table1,True,-1)

DataInterval(0,60,Min,10)
Sample(48,T107_C(),FP2)

EndTable

DataTable(Table2,True,-1)

DataInterval(0,1440,Min,10)
Minimum(1,BattV,FP2,False,False)

EndTable

'Main Program

BeginProg

'Main Scan

Scan(30,Sec,1,0)

'Default CR6 Datalogger Battery Voltage measurement 'BattV'

Battery(BattV)

'Default CR6 Datalogger Wiring Panel Temperature measurement 'PTemp_C'

PanelTemp(PTemp_C,60)

'Turn AM16/32 Multiplexer On

PortSet(U2,1)
Delay(0,150,mSec)
LCount=1
SubScan(0,uSec,16)

'Switch to next AM16/32 Multiplexer channel

PulsePort(U1,10000)

'107 Temperature Probe (4-wire) measurements 'T107_C()' on AM16/32

Therm107(T107_C(LCount),3,U4,U3,0,60,1,0)
LCount=LCount+3
NextSubScan

'Turn AM16/32 Multiplexer Off

PortSet(U2,0)

'Call Data Tables and Store Data

CallTable Table1
CallTable Table2
NextScan

B.4 Full-Bridge Measurement

Up to sixteen full-bridge measurements may be multiplexed through the
AM16/32B. A problem with making full-bridge measurements with this
configuration is that the resistance of the lead wire and multiplexer relays can
cause a voltage drop, reducing the excitation at the bridge. The following
section describes a configuration that compensates for this by measuring the
excitation at the bridge. See CRBasic Example B-4 and TABLE B-4 for a
related program and wiring diagram, or use Short Cut to create your own.

FIGURE B-4. Full-bridge measurement

B-6

Appendix B. Example Programs

TABLE B-4. Wiring for Load Cells CRBasic Example

⏚ (

⏚

CRBasic Example B-4. Load Cells

The following example is a CR1000 program. With minor adjustments, this
program can be used with the CR6 series, CR800 series, or CR3000. This
program measures 16 load cell sensors through an AM16/32B. The AM16/32B
must be in 4x16 mode.

CR1000

Control and COM Terminals Measurement Terminals

VX1 or EX1

Signal Ground)

COM ODD H

COM ODD L

1H COM EVEN H

1L COM EVEN L

COM

12V 12V

G G

C1 CLK

C2 RES

'Declare Variables and Units

Public BattV
Public FCLoaded
Public PTemp_C
Public CReps
Public ZMode
Public CIndex
Public CAvg
Public LCount
Public LoadCell(16)
Public COff(16)
Public Mult(16)={1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
Public Offs(16)={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}

Units BattV=Volts
Units PTemp_C=Deg C
Units LoadCell=mV/V

'Define Data Tables

DataTable(Table1,True,-1)

DataInterval(0,10,Sec,10)
Sample(16,LoadCell(),FP2)
Sample(1,BattV,FP2)
Sample(1,PTemp_C,FP2)

EndTable

DataTable(Table2,True,-1)

DataInterval(0,1440,Min,10)
Minimum(1,BattV,FP2,False,False)

EndTable

'Calibration history table

DataTable(CalHist,NewFieldCal,10)

AM16/32B in 4X16 Mode

Sensors

Odd-numbered H Excitation

Odd-numbered L Ground

Even-numbered H High

Even-numbered L Low

Shield

B-7

Appendix B. Example Programs

SampleFieldCal

EndProg

EndTable

'Main Program

BeginProg

'Initialize calibration variables for

'Generic Full Bridge measurements 'LoadCell()' on the AM16/32 Multiplexer

CIndex=1 : CAvg=1 : CReps=16
For LCount = 1 To 16
COff(LCount)=Offs(LCount)
Next

'Load the most recent calibration values from the CalHist table

FCLoaded=LoadFieldCal(True)

'Main Scan

Scan(10,Sec,1,0)
'Default CR1000 Datalogger Battery Voltage measurement 'BattV'
Battery(BattV)
'Default CR1000 Datalogger Wiring Panel Temperature measurement 'PTemp_C'
PanelTemp(PTemp_C,_60Hz)
'Turn AM16/32 Multiplexer On
PortSet(2,1)
Delay(0,150,mSec)
LCount=1
SubScan(0,uSec,16)
'Switch to next AM16/32 Multiplexer channel
PulsePort(1,10000)
'Generic Full Bridge measurements 'LoadCell()' on the AM16/32 Multiplexer
BrFull(LoadCell(LCount),1,mV25,1,1,1,2500,1,1,0,250,Mult(LCount),COff(LCount))
LCount=LCount+1
NextSubScan
'Zeroing calibration for
'Generic Full Bridge measurements 'LoadCell()' on the AM16/32 Multiplexer
FieldCal(0,LoadCell(),CReps,0,COff(),ZMode,0,CIndex,CAvg)
'Turn AM16/32 Multiplexer Off
PortSet(2,0)
'Call Data Tables and Store Data
CallTable Table1
CallTable Table2
CallTable CalHist
NextScan

B-8

Appendix B. Example Programs

TABLE B-5. Wiring for CS616 Sensor CRBasic Example

⏚ (

CRBasic Example B-5. CS616 Sensors

'Declare Variables and Units

'Main Scan

The following example is a CR1000 program. With minor adjustments, this
program can be used with the CR6 series, CR800 series, or CR3000. This
program measures 48 Campbell Scientific CS616 water content reflectometers
through an AM16/32B. The AM16/32B must be in 4x16 mode. See CRBasic
Example B-5 and TABLE B-5 for a related program and wiring diagram, or
use Short Cut to create your own.

CR1000

AM16/32B in 4X16 Mode

Sensors

1

Control and COM Terminals Measurement Terminals

C2 COM ODD H

1H COM ODD L

1L COM EVEN H

2H COM EVEN L

Signal

Ground)

COM

12V 12V

G G

C1 CLK

C3 RES

1

The red wire for each CS616 connects to the 12V terminal of the datalogger. The clear wire for each CS616 connects to the

G terminal of the datalogger. User-supplied terminal blocks may be required.

Odd-numbered H Sensor 1, 2, and 3 Orange

Odd-numbered L Sensor 1 Green

Even-numbered H Sensor 2 Green

Even-numbered L Sensor 3 Green

Black

Dim LCount
Public BattV
Public PTemp_C
Public VW(48)
Public PA_uS(48)

Units BattV=Volts
Units PTemp_C=Deg C
Units PA_uS=uSec

'Define Data Tables

DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Average(1,VW(1),FP2,False)
Average(1,PA_uS(1),FP2,False)
EndTable

DataTable(Table2,True,-1)
DataInterval(0,1440,Min,10)
Minimum(1,BattV,FP2,False,False)
EndTable

'Main Program

BeginProg

B-9

Appendix B. Example Programs

Scan(5,Sec,1,0)

EndProg

TABLE B-6. Wiring for CR5000 Program Example

⏚ (

'Default CR1000 Datalogger Battery Voltage measurement 'BattV'

Battery(BattV)

'Default CR1000 Datalogger Wiring Panel Temperature measurement 'PTemp_C'

PanelTemp(PTemp_C,_60Hz)
If TimeIntoInterval(0,60,Min) Then

'Turn AM16/32 Multiplexer On

PortSet(3,1)
Delay(0,150,mSec)

LCount=1

SubScan(0,uSec,16)

'Switch to next AM416 Multiplexer channel

PulsePort(1,10000)

'CS616 Water Content Reflectometer measurements 'VW()' and 'PA_uS()' on AM16/32

CS616(PA_uS(LCount),3,1,2,3,1,0)
LCount=LCount+3

NextSubScan
For LCount=1 To 48

VW(LCount)=-0.0663+(-0.0063*PA_uS(LCount))+(0.0007*PA_uS(LCount)^2)

Next

'Turn AM16/32 Multiplexer Off

PortSet(3,0)
EndIf

'Call Data Tables and Store Data

CallTable Table1
CallTable Table2

NextScan

B.5 CR5000 Program Example

CR5000

IXR COM ODD L

Ground)

12V 12V

This CR5000 program uses the AM16/32B in 4x16 mode to measure 16 100 Ω
Platinum Resistance Thermometers (PRTs). See TABLE B-6 for wiring.

AM16/32B in 4X16 Mode

Control and COM Terminals Measurement Terminals

IX1 COM ODD H

7H COM EVEN H

7L COM EVEN L

Signal

COM

G G

C2 CLK

PRT (4 Wires)

Odd-numbered H terminal Excitation

Odd-numbered L terminal Excitation return

Even-numbered H terminal Sense wire excitation side

Even-numbered L terminal Sense wire return side

C1 RES

B-10

CRBasic Example B-6. CR5000 Program Example

'CR5000 Example Program to measure 16 100-ohm Platinum Resistance Thermometers

'connected to an AM16/32B multiplexer used in the 4x16 configuration. The program also

EndProg

'measures 6 copper constantan thermocouples.
'The Thermocouples are connected to differential channels 1-6.

'Declare Variables:

Public TRef, TCTemp(6), PRTResist(16), PRTTemp(16)
Dim LCount 'Counter for setting Array element to correct value for multiplexer measurement

'Declare Output Table for 15 minute averages:

DataTable (Avg15Min,1,-1)

DataInterval (0,5,Min,10)
Average (1,TRef,IEEE4,0)
Average (6,TCTemp(),IEEE4,0)
Average (16,PRTTemp(),IEEE4,0)

EndTable

BeginProg

Scan (60,Sec,3,0)
PanelTemp (TRef,250)
TCDiff (TCTemp(),6,mV20C ,1,TypeT,TRef,True ,0,250,1.0,0)
Portset (1 ,1) 'Set C1 high to Enable Multiplexer
LCount=0
SubScan(0,sec,16)

'Pulse C2 (Set High, Delay, Set Low) to clock multiplexer

Portset (2,1 )
Delay (0,10,mSec)
Portset (2,0)
LCount=LCount+1

'The Resistance measurement measures the PRT resistance:

Resistance (PRTResist(LCount),1,mV50,7,LCountx1,1,500,True ,True ,0,250,0.01,0)

'With a multiplier of 0.01 (1/100) the value returned is R/Ro (Resist/Resist @ 0 deg)
'the required input for the PRT temperature calculation instruction.

NextSubScan
Portset (1 ,0) 'Set C1 Low to disable Multiplexer

'Calculate the Temperature from R/Ro:

PRT (PRTTemp(1),16,PRTResist(1),1.0,0)
CallTable Avg15Min 'Call the DataTable
NextScan

Appendix B. Example Programs

B-11

Appendix B. Example Programs

B-12

NOTE

Appendix C. Thermocouple Measurement

If the AM16/32B will be used in thermocouple measurements, the practices
outlined below should be followed to make the best possible measurement. The
datalogger manuals contain thorough discussions of thermocouple
measurement and error analysis. These topics will not be covered here.

The AM16/32B is not recommended for making highly accurate
thermocouple measurements. Instead, Campbell Scientific
recommends the AM25T, which uses an onboard PRT as a
reference junction.

C.1 Measurement Considerations

C.1.1 Reference Junction

As shown in FIGURE C-1 and FIGURE C-2, two reference junction
configurations are possible: 1) reference located at the datalogger or 2)
reference at the AM16/32B.

C.1.2 Datalogger Reference

If the reference junction is at the datalogger, matching thermocouple wire
should be run between the COM terminals of the multiplexer and the
differential input channel on the datalogger (observe TC wire polarity).

The CR6, CR1000, CR800, CR850, CR3000, and CR5000 have built-in
temperature references. When the reference junction is located at the
datalogger, the signal wires between the datalogger and the AM16/32B must be
of the same wire type as the thermocouple (FIGURE C-1). The “polarity” of
the thermocouple wires must be maintained on each side of the multiplexer (for
example, if constantan wire is input to an L terminal, then a constantan wire
should run between the multiplexer’s COM ODD L terminal and the
datalogger measurement terminal). FIGURE C-1 and FIGURE C-2 depict type
T thermocouple applications, but other thermocouple types (for example, E, J,
and K) may also be measured and linearized by the dataloggers.

It is not recommended to make measurements of any other sensor type through
the AM16/32B if thermocouples are measured with respect to the datalogger
reference (the signal wires between the datalogger and AM16/32B are made of
thermocouple wire). Two problems would arise due to the properties of
thermocouple wire.

First, an extraneous thermocouple voltage would be added to the non­thermocouple signal at the junction of dissimilar metals (for example, the
multiplexer COM terminals). The magnitude of this signal would vary with the
temperature difference between the datalogger and the AM16/32B.

C-1

Appendix C. Thermocouple Measurement

Second, some thermocouple wires have a greater resistance than copper, which
adds resistance to the non-thermocouple sensor circuit. For example,
constantan is approximately 26 times more resistive than copper.

FIGURE C-1. Differential thermocouple measurement with reference

junction at the datalogger

FIGURE C-2. Differential thermocouple measurement with reference

junction at the AM16/32B (using 107-L thermistor)

C.1.3 AM16/32B Reference

An external reference, usually a thermistor, can be located at the AM16/32B, as
shown in FIGURE C-2. This approach requires an additional single-ended
datalogger input to measure the reference. Position the reference next to the
COM terminals and, when practical, measure the thermocouples on SETs that
are in close proximity to the COM terminals in order to minimize thermal
gradients.

C.1.4 Thermal Gradients

Thermal gradients between the AM16/32B’s measurement terminals and COM
terminals can cause errors in thermocouple readings. For example, with type T
thermocouples, a one-degree gradient between the input terminals and the
COM terminals will result in an approximate one-degree measurement error.
Installing the aluminum cover plate (FIGURE C-3) (pn 19237) helps to
minimize gradients. For best results, the AM16/32B should be shielded and
insulated from all radiant- and conducted-thermal sources. When an enclosure
is used, gradients resulting from heat conducted along the thermocouple wire
can be minimized by coiling some wire inside the enclosure. This technique
allows heat to largely dissipate before it reaches the terminals. If the

C-2

Appendix C. Thermocouple Measurement

AM16/32B is housed in a field enclosure, the enclosure should be shielded
from solar radiation.

FIGURE C-3. AM16/32B aluminum cover plate

C-3

Appendix C. Thermocouple Measurement

C-4

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