Campbell SDM-IO16A Product Manual
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Campbell SDM-IO16A Product Manual

16-channel input/output expansion module
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09/2020
Copyright ©
2020
Campbell Scientific, Inc.

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Summary of Contents for Campbell SDM-IO16A

  • Page 1 09/2020 Copyright © 2020 Campbell Scientific, Inc.

  • Page 2: Table Of Contents

    Table of contents 1. Introduction 2. Specifications 2.1 General 2.2 Terminal specifications (output mode) 2.3 Terminal specifications (input mode) 2.4 Pulse counting specifications 3. Installation 3.1 Power considerations 3.2 Terminal connections 3.3 Address selection switches 4. Programming the data logger 4.1 General principles 4.2 SDMIO16() instruction 4.3 SDMCD16AC() instruction...

  • Page 3: Introduction

    The SDM-IO16A is a synchronously addressed data logger peripheral. Data logger control terminals 1, 2 and 3 are used to address the SDM-IO16A and exchange digital data with it. This module uses advanced error checking techniques to ensure correct transmission of data to and from the module.

  • Page 4: Specifications

    SDM port: 0/5 V logic level port compliant with the requirements of the Campbell Scientific SDM protocol — this is designed for connection to the data logger SDM port. SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 5: Terminal Specifications (Output Mode)

    188 x 64 x 22 mm (7.4 x 2.5 x 0.9 in) Mounting: Mounting brackets have two holes at 177.8 mm (7 in) nominal spacing. Mounting screws and plastic inserts suitable for use with Campbell Scientific enclosures are also supplied. Weight: 175 g (6.2 oz) EMC status:...

  • Page 6: Pulse Counting Specifications

    If more detailed input/output characteristics are required, experienced users should consult the equivalent circuit diagrams and graphs shown in FIGURE 2-1 (p. 5). General principles of pulse and frequency measurements (p. 20) for a more detailed discussion. SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 7 (a) Input biasing and protection (b) Output set ON (c) Output set OFF (d) Output voltage versus current output (e) Output voltage versus resistive load FIGURE 2-1. Simplified equivalent terminal circuits and graphs of output voltage SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 8: Installation

    3. Installation For correct operation, the SDM-IO16A must be installed where there is no risk of water ingress or condensation. WARNING: The order in which connections are made is critical. Always connect 12 V first, followed by ground, then the SDM control terminals.

  • Page 9: Terminal Connections

    When being used for control and outputting current the SDM-IO16A power requirements will be large compared to most Campbell Scientific products when driving significant loads. For this type of application an external power supply, as shown in FIGURE 3-1 (p. 7) (b), is recommended to power the SDM-IO16A.

  • Page 10: Address Selection Switches

    The factory-set address is 00. Table 3-2 (p. 8) shows switch position and the corresponding address. FIGURE 3-3 (p. 9) shows the position of the switch. Table 3-2: SDM-IO16A SDM address settings Switch Setting Decimal Address Base 4 Address SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 11 Switch Setting Decimal Address Base 4 Address F (reserved) FIGURE 3-3. Address selection switch Each SDM-IO16A must be set to a unique address on the SDM bus, so no two SDM peripherals share the same address. SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 12: Programming The Data Logger

    The module is reconfigured from the controlling program to allow for more demanding applications. In most cases, though, on power-up the I/O terminals of the SDM-IO16A default to input mode, with no switch debounce filtering and measurement of frequency and duty cycle automatically starts for all terminals.

  • Page 13: Sdmio16() Instruction

    5, Mode4_1, Multiplier, Offset) Remarks The terminals on the SDM-IO16A are configured for either input or output. When configured as input, the SDM-IO16A measures the logical state of each terminal, counts pulses, and measures the frequency of and determines the duty cycle of applied signals. It is also possible to make the SDM-IO16A generate an interrupt signal to the data logger when one or more input signals change state.
  • Page 14 If the command is successful a 0 is returned; otherwise, the value is incremented by 1 with each failure. SDMAddress This parameter defines the address of the SDM-IO16A with which to communicate. Valid SDM addresses are 0 through 14. Address 15 is SDMTrigger reserved for the instruction.

  • Page 15: Sdmcd16Ac() Instruction

    4.3 SDMCD16AC() instruction SDMCD16AC() All but the oldest versions of the CR5000 operating system also support the instruction to control the SDM-IO16A for output mode only. This instruction should only be used SDMIO16() if backward compatibility is required, as only supports error detection on communications between the module and the data logger.

  • Page 16: Sdmspeed() Instruction

    General principles (p. 10). A summary table of common command codes is shown in Table 4-2 (p. 18). The small number of different types of action allows the commands to be grouped: SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 17 4096 seconds (low-speed mode) and 1024 seconds (high-speed mode). The value output is a number between 0 and 100 that indicates the percentage of time the terminal was high. SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 18 0 sets it to output. On power-up, terminals default to being inputs. If the direction is set to be an output immediately after power- up the state will be low. SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 19 These are a watchdog error counter which is incremented if the module crashes because of a software or hardware failure that required the SDM-IO16A to be reset and a communications error counter which represents the number of times SDM communications between the data logger and SDM-IO16A failed.
  • Page 20 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 cycle 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 debounce Set-up terminals Read 91 or 92 state 93 or 94 state SDM-IO16A 16-Channel Input/Output Expansion Module...
  • Page 21 Table 4-2: Common command codes (in italics) relative to terminal number and function 95 or 96 direct Set int 97 or 98 mask Set low- speed mode Set high- speed mode SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 22: Appendix A. General Principles Of Pulse And Frequency Measurements

    A.1 Introduction It is necessary to understand the general method of input measurements of the SDM-IO16A to understand the limits of frequency and duty cycle resolution. The microprocessor in the module runs an internal task that reads the status of all 16 terminals at a fixed sample rate of 4096 Hz (low-speed mode) and 16384 Hz (high-speed mode).

  • Page 23: Resolution Of Frequency Measurements

    The resolution is calculated using the following equation: %r = 100 × f / (sample rate ×Int (t × f)) SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 24: Debounce Filtering

    This action emulates a traditional resistive capacitive (RC) filter, except that the integrator changes in a linear fashion. The amount by which the counter is changed decreases with increasing size of the debounce timer parameter. SDM-IO16A 16-Channel Input/Output Expansion Module...

  • Page 25: Using The I/O Line To Trigger Code To Run On A Data Logger

    The SDM-IO16A can be configured, using the terminal setup commands (86 to 90), to generate an "interrupt" signal back to the data logger when input terminals change state. When configured, the SDM-IO16A will pulse its I/O line until the data logger responds by reading the SDMIO16()
  • Page 26 I/O line is pulsed. That code could simply read the SDM-IO16A port status. It may also trigger sending alarms or recording times of an event. See the program example on the Campbell Scientific website (www.campbellsci.com/downloads/sdm-io16a-program-example) to see a demonstration...
  • Page 27 See Product Details on the Ordering Information pages at www.campbellsci.com. Other manufacturer's products, that are resold by Campbell Scientific, are warranted only to the limits extended by the original manufacturer.
  • Page 28 Campbell Scientific office serves your country. To obtain a Returned Materials Authorization or Repair Reference number, contact your CAMPBELL SCIENTIFIC regional office. Please write the issued number clearly on the outside of the shipping container and ship as directed.
  • Page 29 Do not recharge, disassemble, heat above 100 °C (212 °F), solder directly to the cell, incinerate, or expose contents to water. Dispose of spent batteries properly. 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...
  • Page 30 Campbell Scientific regional offices Australia France Thailand Location: Garbutt, QLD Australia Location: Vincennes, France Location: Bangkok, Thailand Phone: 61.7.4401.7700 Phone: 0033.0.1.56.45.15.20 Phone: 66.2.719.3399 Email: info@campbellsci.com.au Email: info@campbellsci.fr Email: info@campbellsci.asia Website: www.campbellsci.com.au Website: www.campbellsci.fr Website: www.campbellsci.asia Brazil Germany Location: São Paulo, SP Brazil...

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