SDM-SW8A 8-Channel Switch Closure Input Module

Name: SDM-SW8A - 8-Channel Switch Closure Input Module
Brand: Campbell Scientific

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Digital Input Peripherals / SDM-SW8A

SDM-SW8A 8-Channel Switch Closure Input Module

Expands Data Logger Input Channels
For switch closure or voltage pulse sensors

Overview

Your data logger can measure more switch closures or voltage pulses with an SDM-SW8A. Sensors that output a switch closure or voltage pulse signal include tipping bucket rain gages, flow meters, and anemometers.

Well suited for use in energy management studies
Provides eight individually configured channels
Measures a variety of signals: reed switches, dry contacts, or slow voltage pulses
Allows up to four SDM-SW8As to be connected to a single data logger

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Detailed Description

The SDM-SW8A provides eight channels for connecting the sensors. Each channel is individually configured for single-pole double-throw (SPDT), single-pole single-throw (SPST), or voltage pulse measurements. Output options include counts, duty cycle, and state.

SDM Operation

The data logger enables individual modules through an addressing scheme; multiple SDMs (in any combination) can be connected to one data logger. We recommend a maximum of four SDM-SW8As be connected to a single data logger. After a module is enabled, it operates independently of the data logger until additional commands are received or results are transmitted.

Specifications

Measurement Types	Switch closure (SPDT, SPST), dc voltage pulse
Input Voltage Threshold	From below 0.9 to above 4.0 Vdc (±20 Vdc maximum)
Maximum Input Frequency	100 Hz (50% duty cycle)
Minimum Input Pulse Width	5 ms high, 5 ms low
Maximum Bounce Time	3 ms open without counting
Output Options	State, duty cycle, counts
Maximum Count/Port	65535
Internal Sampling Frequency	500 Hz
Watchdog Reset	Yes
Operating Temperature Range	-25° to +55°C
Operating Voltage Range	9.6 to 16 V
Typical Current Drain	3 mA quiescent 6 mA active (maximum)
Relative Humidity	0 to 90% RH (non-condensing)
Maximum Cable Length	6 m (20 ft) total to all SDM devices Consult Campbell Scientific if longer lengths are necessary.
Dimensions	15.7 x 6.9 x 2.3 cm (6.2 x 2.7 x 0.9 in.)
Weight	0.23 kg (0.5 lb)

Compatibility

Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product	Compatible	Note
21X (retired)
CR10 (retired)
CR1000
CR1000X
CR10X (retired)
CR200X (retired)
CR206X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired)
CR295X (retired)
CR3000		For the CR3000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR500 (retired)
CR5000 (retired)		For the CR5000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR510 (retired)
CR6
CR800
CR850
CR9000 (retired)
CR9000X

Mounting Equipment

Product	Compatible	Note
ENC10/12
ENC10/12R
ENC12/14
ENC14/16
ENC16/18
ENC24/30
ENC24/30S

Additional Compatibility Information

Data Logger Considerations

Programming

In the CRBasic data loggers, the SDM-SW8A operation is controlled by the SDMSW8A instruction. Instruction 102 controls the SDM-SW8A operation for Edlog data loggers that were shipped after October 1988 (consult Campbell Scientific for equipment shipped prior to this date).

Power Supply

Due to the 3 mA continuous and 6 mA active current drain, an auxiliary 12 Vdc power supply is recommended for powering the SDM-SW8A in remote, long-term applications.

For some applications, it may be convenient to use the data logger power supply. You can do this where ac power is available, or where a solar panel can be used for recharging the data logger's sealed rechargeable battery.

Enclosure Considerations

The SDM-SW8A requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. Grommets and screws are provided to attach the SDM-SW8A to the backplate of our enclosures.