Campbell Scientific SDM-AO4 User Manual
SDM-AO4 Four Channel Analog
12V
C1
C2
C3
Output Module
SDM-AO4
4 CHANNEL ANALOG OUTPUT
Revision: 4/09
AO1
AO2
AO3
A04
SN: 2270
MADE IN USA
Copyright © 1986-2009
Campbell Scientific, Inc.
Warranty and Assistance
The SDM-AO4 FOUR CHANNEL ANALOG OUTPUT MODULE is
warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in
materials and workmanship under normal use and service for twelve (12)
months from date of shipment unless specified otherwise. Batteries have no
warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is
limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option)
defective products. The customer shall assume all costs of removing,
reinstalling, and shipping defective products to CAMPBELL SCIENTIFIC,
INC. CAMPBELL SCIENTIFIC, INC. will return such products by surface
carrier prepaid. This warranty shall not apply to any CAMPBELL
SCIENTIFIC, INC. products which have been subjected to modification,
misuse, neglect, accidents of nature, or shipping damage. This warranty is in
lieu of all other warranties, expressed or implied, including warranties of
merchantability or fitness for a particular purpose. CAMPBELL SCIENTIFIC,
INC. is not liable for special, indirect, incidental, or consequential damages.
Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company
serves your country. To obtain a Returned Materials Authorization (RMA),
contact CAMPBELL SCIENTIFIC, INC., phone (435) 753-2342. After an
applications engineer determines the nature of the problem, an RMA number
will be issued. Please write this number clearly on the outside of the shipping
container. CAMPBELL SCIENTIFIC's shipping address is:
CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
SDM-AO4 Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.
1. Function........................................................................1
2. Specifications ..............................................................1
3. Power Supply...............................................................1
4. Physical Connections .................................................2
5. Addressing...................................................................3
6. Programming ...............................................................6
6.1 CRBasic....................................................................................................6
6.1.1 SDMAO4 Instruction......................................................................6
6.1.2 SDMSpeed Instruction....................................................................7
6.2 Edlog.........................................................................................................8
6.3 Programming Examples............................................................................8
6.3.1 CR5000 Program Example.............................................................9
6.3.2 CR10X Program Example ............................................................10
List of Figures
1. Front Panel of the SDM-AO4.....................................................................3
2. Locational Diagram for the Address Jumpers ............................................5
List of Tables
1. Description of Terminal Block Connections..............................................3
2. SDM-AO4 Addressing...............................................................................4
3. Bit Period Value .........................................................................................7
4. Description of Instruction 103....................................................................8
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SDM-AO4 Four Channel Analog Output
1. Function
The SDM-AO4 is designed to output four continuous voltages at levels set by
a Campbell Scientific datalogger.
2. Specifications
Power Requirements
Operating voltage: 12 VDC Nominal (9.6 V - 16 V)
Typical current drain: 10.5 mA
3. Power Supply
Physical Specification
Size: 6.1" X 2.7" X 1.1"
Weight: 0.9 lbs.
Analog Output
Range: ±5000 mV
Resolution 2.5 mV
Maximum Current 1 mA
Accuracy ± (0.5% of |Vout| +5 mV)
Minimum load
(for above accuracy) 75, 000 ohms
Output Resistance
Temperature Range
-25 to +55
1
Output resistance can be viewed as a series resistance with the load the SDMAO4 is driving. A low resistance load will cause appreciable error due to the
voltage drop across the 200 ohm resistance. For example, the error (in addition
to the accuracy specification above) with a 4800 ohm load = 200 / (4800 +
200) * Vout = 4 % of Vout
It is often convenient to power the SDM-AO4 from the datalogger power
supply, but when doing so consideration must be given to the SDM-AO4's
10.5 mA continuous current drain. The alkaline supply available with the
datalogger has 7.5 Amp-hours and will power one SDM-AO4 for less than one
month. This supply is not recommended for continuous long-term operation.
The rechargeable lead acid option, float charged by an AC supply or solar
panel, may be used for long term operation.
o
C
1
200 Ohms
The SDM-AO4 may also be powered from an external 12 Volt supply,
independent from the datalogger supply. The low side of an external 12 Volt
supply should be connected to datalogger ground and not directly earth
grounded. Slight alterations in ground potential across the 21X terminal strip
are created when the 21X 12 Volt supply is used to power peripherals.
Therefore, low level voltage measurements (e.g., thermocouples, thermopiles,
and radiometers) should be made differentially when powering the SDM-AO4
with the 21X 12 Volt output.
1
SDM-AO4 Four Channel Analog Output
4. Physical Connections
Figure 1 shows the front panel of the SDM-AO4. The terminal block on the
left is used for connection to the datalogger and the terminal block on the right
provides the continuous analog output. The two ground ports on the left block
are identical and at the same potential.
Table 1 describes the terminal block connections. Multiple SDM-AO4s may
be used by connecting the datalogger side of one SDM-AO4 to the next.
Campbell Scientific does not recommend connecting more than six SDMAO4s to one datalogger.
The CABLE5CBL-L or similar cable is used to connect the module to the
datalogger. A 1-ft cable length should be sufficient when both datalogger and
module are housed within an ENC12/14 enclosure; a 2-ft length may be
required if the datalogger and SDM-AO4 are housed at opposite ends of an
ENC16/18 enclosure.
CRBasic dataloggers should use the SDMSpeed instruction if the cable length
is longer than 20 feet (see Section 6.1.2). The maximum recommended cable
length for the CR7 is 600 ft. For other Edlog dataloggers, the maximum
recommended cable length is 20 feet.
CAUTION
CAUTION
Cables connecting the terminals of the datalogger and
SDM device should be as short as possible to minimize the
risk of corruption of the signal and damage from induced
surges.
With power supplied to an SDM-AO4 and before execution of the datalogger
program, a random voltage between ±5 Volts will be output. To avoid
outputting erroneous voltages to the receiving device, connect the SDM-AO4
to the datalogger, start the program, and then connect the receiving device.
The order of connections is critical. ALWAYS CONNECT
GROUND FIRST, followed by 12V and then the Control
Ports.
2
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