Includes Internal Microprocessor
Allows independent measurement intervals
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Overview

The SDM-INT8 outputs timing data to a Campbell Scientific datalogger. The datalogger can process the timing data to calculate RPM, duty cycle, velocity, crank angle, etc.

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Benefits and Features

  • Allows individual programming for each of the eight channels
  • Includes an internal microprocessor that allows measurement independent of datalogger's execution interval
  • Outputs period, pulse width, frequency, counts, or time intervals
  • Records results as execution interval averages, continuous averages, specified interval averages, or capture all events

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Detailed Description

The SDM-INT8 has eight channels that are individually programmed to record the timing of input voltage transitions (events). It uses this information to output:

  • Period (ms)
  • Frequency (kHz)
  • Elapsed time between events on adjacent channels
  • Number of counts measured on channel 2 between a “start” event on channel 1 and a “stop” event on any other channel
  • Elapsed time between events on channel 1 and any other channel
  • Pulse Counting (any channel can function as a pulse counter)

High Level Voltage Input Pulses Schematic

Low Level AC Voltage Input Schematic

SDM Operation

The datalogger enables individual modules through an addressing scheme; up to 16 SDM-INT8s can be connected to one datalogger. After a module is enabled, it operates independently of the datalogger until additional commands are received or results are transmitted.

Specifications

General

Operating Voltage 9.6 to 16 Vdc
Current Drain
  • 13 to 20 mA (active)
  • 400 µA (quiescent)
Maximum Timing Measurement 16.7 s
Resolution ±1 µs
Operating Temperature -25° to +50°C
Dimensions 0.3 x 12.7 x 2.5 cm (8 x 5 x 1 in.)
Weight 0.82 kg (1.8 lb)

High-Level Voltage Input Pulses

Minimum Pulse Width 2 µs
Maximum Frequency (32-bit values)
  • The maximum frequency specification for high-resolution (32-bit) values assumes all eight channels are used.
  • 5.1 kHz (averaging options)
  • 10 kHz (capturing all events)
Maximum Frequency (16-bit values)
  • The maximum frequency specifications for low-resolution (16-bit) values is for the execution interval averaging only.
  • If number of channels programmed is
    • 1 channel—42.5 kHz
    • 2 channels—17.5 kHz
    • 3 channels—11 kHz
    • 4 channels—8.6 kHz
    • 5 channels—5.2 kHz
    • 6 channels—4.8 kHz
    • 7 channels—4.5 kHz
    • 8 channels—4.28 kHz

Low-Level AC Voltage Input

AC Voltage
  • 20 mV RMS (min.) ac voltage
  • 20000 mV RMS (max.) ac voltage
Input Hysteresis 11 mV
Minimum Frequency 1 Hz
Maximum Frequency
  • 100 kHz (20 mV min. RMS)
  • 400 kHz (50 mV min. RMS)
  • 1000 kHz (150 mV min. RMS)
  • 4000 kHz (2.5 to 20 V min. RMS)

Compatibility

Datalogger Considerations

Programming

The SDMINT8 instruction controls the SDM-INT8 operation in CRBasic. Instruction 101 controls the SDM-INT8 operation in Edlog.

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X CR6
*

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR5000 CR7X CR9000
* #

Datalogger Notes:
*For the CR3000 and CR5000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.

#For the CR7, SDMs connect to the C1, C2, and C3 terminals provided on the 700X control module (after Sept 1996).

†On the CR9000X, SDMs connect to ports provided on the CR9032 CPU module.

♣On the CR9000, SDMs connect to ports provided on the CR9080 PAM module.

Power Considerations

The SDM-INT8 draws 20 mA. In most applications, the datalogger’s sealed rechargeable power supply can be used. The datalogger’s alkaline power supply has sufficient capacity to operate the SDM-INT8 during short-term installations only.

Enclosure Considerations

The SDM-INT8 should be housed in an environmental enclosure. A bracket is shipped with the SDM-INT8 for mounting it to an enclosure backplate.

Compatible Enclosures

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

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