Onset S-CIA-CM14 User manual

12-Bit 4–20 mA Input Adapter (S-CIA-CM14) Manual
7583-C MAN-S-CIA
The 12-Bit 4–20 mA Input Adapter is used for sensors with 4–20 mA current loop outputs and is
designed to work with the HOBO® stations. The input adapter features both a battery-saving
switched input and a non-switched input. It also provides a trigger source voltage for
controlling power to external sensors. The input adapter has a plug-in modular connector that
allows it to be added easily to a HOBO station.
Specifications
Measurement Range* 4–20 mA
Accuracy ± 0.1 mA (± 0.5% full scale) over full temperature range of -40°C to
75°C (-40°F to 167°F)
Resolution ±4.93 µA
Input Impedance 124 Ω
Switched Input Maximum switch voltage above ground (Pin 2 to Pin 1): 20 V
Maximum switch current: 50 mA
On time: 316.6 ms ±3%
Sensor Trigger: Source Voltage: 2.5 V ±2.4%; maximum current: 1 mA
On time: 12.7 ms ±3%
Operating Temperature Range -40°C to 75°C (-40°F to 167°F)
Housing Plastic case; must be placed inside logger enclosure to protect from
direct exposure to the weather
User Connection Six-position screw terminal strip (16–30AWG); shielded cable
recommended with outside diameter of 3.2 to 3.8 mm (0.125 to
0.150 in.)
Dimensions 4.5 x 4.8 x 1.6 cm (1.8 x 1.9 x 0.6 in.)
W
eight 25 g (0.88 oz)
Number of Data Channels** 1
Measurement Averaging Option Yes
Digital Filtering Automatic digital filtering with 32 readings/sample in 16.6 ms
Bits per Sample 12
Length of Smart Sensor
Network Cable**
14 cm (5.5 in.)
The CE Marking identifies this product as complying with all relevant
directives in the European Union (EU).
* The input adapter can provide readings as low as 0 mA. This can be helpful when diagnosing sensor issues such as open
inputs.
** A single station can accommodate 15 data channels and up to 100 m (328 ft) of smart sensor cable (the digital
communications portion of the sensor cables), although available space in the enclosure may limit the number of
sensors you can attach.
Mounting
Use the self-adhesive hook-and-loop tape included in the package to mount the input adapter
inside the logger enclosure. To mount more than one adapter, use the back of the logger
enclosure door.
For the HOBO Micro Station, you can place the input adapter inside the logger enclosure and
allow it to float freely. It is not necessary to use the hook-and-loop tape.
Mounting Considerations
•If sensor cables are left on the ground, use a conduit to protect against animals, lawn
mowers, exposure to chemicals, etc.
•Refer to the logger manual for additional details on mounting.
12-Bit 4–20 mA
Input Adapter
S-CIA-CM14
Items Included:
•Hook and loop tape
•Cable ties
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12-Bit 4–20 mA Input Adapter (S-CIA-CM14) Manual
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Attaching Sensor Cables
Insert the cable through the opening at the bottom of the
logger enclosure as described in the logger manual. Be sure to
provide “drip loops” underneath the logger to prevent water
from trickling up the cable and into the logger.
Use the included cable tie to provide strain relief to the cable
(or individual wires), as shown below.
Cable Strain Relief
Sensor Input Connections
The 12-Bit 4–20 mA Input Adapter utilizes a 6-position screw-
terminal block for sensor connections with wire sizes ranging
from 16 to 30AWG. Pin numbers, names and descriptions are as
follows:
Pin # Pin Name Definition
1 GROUND Ground. Used as a common
connection.
2 SWITCHED YELL
(+)
Yellow switched. Makes connection to
Pin 3 (+ Yellow) once per sample. This
helps to conserve external sensor
battery life. Maximum 20 V, 50 mA.
See Operation for timing diagrams.
3 YELLOW (+) Positive current input for sampling.
4 TRIG. SOURCE Triggered source. Provides voltage
from the logger’s battery to power, or
trigger, the external circuitry.
Maximum 2.5 V, 1 mA. See Operation
below for timing diagrams.
5 BLUE (-) Negative current input for sampling.
6 SHIELD Connects cable shield for noise
suppression and circuit protection.
Typical Setup
A typical remote data logging setup consists of a 12-Bit 4-20 mA
Input Adapter, a two-wire 4-20 mA transducer (i.e. flow,
pressure, pH, etc.), and an external battery to provide
transducer power.
Switched Connection
If battery conservation is not an issue, or if longer transducer
warmup time is required, the following non-switched
connection can be made.
Non-switched Connection
Connecting the Adapter to a logger
To use the 12-Bit 4–20 Volt Input Adapter, stop the logger and
insert the adapter’s modular jack into an available sensor
connection port on the logger.
The logger automatically detects the new input adapter the
next time you launch it. Launch the logger and verify that the
input adapter is functioning correctly. Measurements are
recorded in milliamps (mA). See the logger manual for details.
Operation
The 12-Bit 4–20 mA Input Adapter uses digital filtering and
optional measurement averaging to reduce the effect of noise
and improve accuracy.
Regardless of whether measurement averaging is used or not,
each sample is comprised of a 300 ms (±3%) warmup period
and a 16.6 ms (±3%) sample period. During the sample period,
digital filtering is accomplished by taking 32 readings. These
readings are then averaged to produce a single measurement,
as shown in the following diagram:
Measurement Averaging (Not to Scale)
Optional measurement averaging can be selected at launch.
Use measurement averaging if measurements may fluctuate
significantly within the logging interval. Measurement
averaging helps to prevent the sampling error known as
aliasing.
To use measurement averaging, set the Sampling Interval to a
rate that is faster than the logging interval. When measurement
averaging is selected in this way, the adapter takes several
measurements during the logging interval and averages them
to produce a single logged data point. For example, if the
logging interval is 10 minutes and the sampling interval is 1
minute, each recorded data point is the average of 10
measurements.
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12-Bit 4–20 mA Input Adapter (S-CIA-CM14) Manual
© 2003–2017 Onset Computer Corporation. All rights reserved. Onset and HOBO are trademarks or registered
trademarks of Onset Computer Corporation. All other trademarks are the property of their respective
companies.
7583-C MAN-S-CIA
Note that fast sampling intervals (less than one minute)
significantly reduce battery life.
For more information about sampling intervals, refer to the
logger manual.
Using the Switched Input
The 12-Bit 4–20 mA Input Adapter can be used with
continuously powered 4–20 mA transducers as well as remote
applications with external battery-powered 4–20 mA
transducers. (See figures in Typical Setup.)
To take advantage of the switched input, the 4–20 mA
transducer must meet the following criteria:
•The sensor must be able to be powered from the 4–20 mA
loop.
•The sensor must have a warmup time of less than 300 ms.
Using the switched input can significantly reduce external
battery consumption because the transducer is powered only
during warmup and sampling, as shown in the following
diagram, instead of being powered continuously.
Logging with Switched Input
Note
•Using an external battery to drive the 4–20 mA transducer
does not increase the battery life of the logger.
Compared with continuously powering the 4–20 mA
transducer, the average current drain is significantly reduced.
For an example of the power savings with and without using
the switched input:
•If the logger’s sampling interval is 60 seconds and the
worst case current drain for the transducer is 20 mA, then
the average current drain will be:
transducer current × sample duration ÷ sampling
interval
20 mA × 0.327 s ÷ 60 s = 0.109 mA
•If we assume that the transducer battery used has a useful
capacity of 2000 mAh, the battery life is:
battery capacity ÷ average current
2000 mAh ÷ 0.109 mA ÷ 24 hr/day = 764 days
•Without switched input, the battery life would be:
2000 mAh ÷ 20 mA ÷ 24 hr/day = 4.1 days
Therefore, using the switched input allows the device to run
approximately 186 times longer!
Maintenance
With normal usage, if the adapter is installed correctly, the
adapter’s circuitry is protected against excessive moisture and
does not require any maintenance or cleaning. However, in an
unusually wet environment, excessive moisture can collect in
the logger enclosure and adversely affect measurement
accuracy and communications in the adapter module.
The circuit board is conformal coated to provide limited
protection against moisture, but if you observe heavy
condensation, consider the following options:
•Verify that the logger is installed properly and sealed
according to the instructions given in the logger user
manual.
•Consider moving the logger to a location that is better
protected from moisture, is better ventilated, or receives
some sunlight to help keep the logger dry.
•Apply WD-40, LPS 1, or 711 to the six-position terminal
block and the modular connectors to displace moisture
and help prevent corrosion. (Other spray lubricants may
be appropriate; check product labeling to ensure that it is
safe to use on plastics and electronics.)
Verifying Accuracy
You should check the accuracy of the 12-Bit 4–20 mA Input
Adapter annually. Verify the accuracy of the input adapter
against a known standard, such as a calibrated voltage source.
If it is not providing accurate data, it may have been damaged.
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