Digital Peripherals / SDM-SIO4
RETIRED ›
This product is no longer available and has been replaced by: SDM-SIO4A. Some accessories, replacement parts, or services may still be available.
SDM-SIO4 4-Channel Serial I/O Module

Overview

The SDM-SIO4 is a legacy product and should be purchased only as a replacement or for use with legacy dataloggers such as the CR10X. When considering the purchase of an SDM-SIO4, first consider using the SDM-SIO1 instead. Please note that the SDM-SIO4 is not compatible with all dataloggers.

Primarily for legacy dataloggers, the SDM-SIO4 adds serial I/O capacity and flexibility. It has four serial ports that communicate with serial sensors, display boards, printers, and other serial devices. After being programmed, the SDM-SIO4 communicates with connected devices in parallel with the datalogger's own program sequence.

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Benefits and Features

  • Provides four configurable serial RS-232 ports
  • A multitasking operating system allows concurrent transmission and receipt of data on all ports.

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Detailed Description

The SDM-SIO4 is a legacy product and should be purchased only as a replacement or for use with legacy dataloggers such the CR10X. When considering the purchase of an SDM-SIO4, first consider using the SDM-SIO1 instead. Please note that the SDM-SIO4 is not compatible will all dataloggers.

Specifications

Communication Rate Speed at which data is transferred is controlled by the datalogger and can vary with the microprocessor activity as well as the length of the SDM cables.
Typical Transfer Rate One byte per millisecond
Power Supply Unregulated 12 V supply, 9 to 18 Vdc
Internal Battery Retains configuration information only. (Lithium battery has an estimated life of 10 years.)
Number of Ports 4 (independently configurable for different serial data formats)
Serial Ports Baud Rate 25 to 115,200 bps
Port Output
  • 0 to 5 V logic
  • ±5 V for RS-232 (switchable)
Port Configuration 9-pin D connectors
Data Flow Control By datalogger or SDM-SIO4, if required, using hardware or software protocols
Onboard Diagnostics Built-in system watchdog resets the processor in the event of a crash caused by transients and a built-in LED gives an indication of SDM-SIO4 status on power-up.
Input Voltage Limits ±25 V
Operating Temperature Range -25° to +50°C
Dimensions
  • 18.3 x 8.9 x 3.6 cm (7.2 x 3.5 x 1.4 in.)
  • 22.4 x 8.9 x 3.6 cm (8.8 x 3.5 x 1.4 in.) with mounts
Weight 499 g (1.1 lb)

Current Drain

All Ports Active 40 mA
Quiescent 0.7 mA (quiescent state entered if there is no SDM or port activity for ~30 ms)

Buffers (each port)

Type Fill & stop (Once filled, additional data received is lost.)
Receive (Rx) 981 bytes + 16-byte hardware buffer
Transmit (Tx) 981 bytes + 16-byte hardware buffer
Processed Data Storage 891 bytes (suitable for storing 224 4-byte Campbell Scientific floating point values)
Floating Point Buffer Used only when the datalogger outputs floating point data via the SDM. This buffer is 241 bytes—sufficient for 60 floating-point values.

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) To use the SDM-SIO4 with a CR10 requires a six-conductor cable instead of a five-conductor cable. The extra conductor attaches to control port 6,7, or 8. A Library Special PROM with Instruction 113 is also required.
CR1000 Although the SDM-SIO4 is technically compatible with the CR1000, Campbell Scientific recommends using one or more of the SDM-SIO1 instead.
CR10X (retired) To use the SDM-SIO4 with a CR10X requires a six-conductor cable instead of a five conductor cable. The extra conductor attaches to control port 6,7, or 8. The operating system must be CR10X OS version 1.4 or later.
CR200X (retired)
CR206X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired)
CR295X (retired)
CR3000 Although the SDM-SIO4 is technically compatible with the CR3000, Campbell Scientific recommends using one or more of the SDM-SIO1 instead.

SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR500 (retired)
CR5000 (retired) SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR510 (retired)
CR6
CR800 Although the SDM-SIO4 is technically compatible with the CR800, Campbell Scientific recommends using one or more of the SDM-SIO1 instead.
CR850 Although the SDM-SIO4 is technically compatible with the CR850, Campbell Scientific recommends using one or more of the SDM-SIO1 instead.
CR9000 (retired) SDMs connect to ports provided on the CR9080 PAM module.
CR9000X SDMs connect to ports provided on the CR9032 CPU module.

Mounting Equipment

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

Additional Compatibility Information

Note: Future dataloggers may not support the SDM-SIO4, and therefore it is only recommended for existing networks that already contain this interface.

Datalogger Considerations

Programming

The SDMSIO4 Instruction controls the SDM-SIO4 operation in CRBasic. Instruction 113 controls SDM-SIO4 operation in Edlog (a Library Special PROM may be required in older dataloggers).

Power Requirements

Because of the minimal current drain (0.7 mA quiescent, 40 mA with all four ports active), the SDM-SIO4 is typically powered directly from the datalogger. A supplementary power supply may be required for some applications, especially where more than one SDM is operated by a single datalogger.

Enclosure Considerations

The SDM-SIO4 requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. The SDM-SIO4's case has mounting flanges for attachment to the 1"-on-center hole grid of Campbell Scientific enclosures. Grommets and screws are provided to attach the flanges to the backplate of our enclosures.


Frequently Asked Questions

Number of FAQs related to SDM-SIO4: 5

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  1. The battery is a CR2032 button cell lithium battery that is user replaceable. However, after the case is opened, proper ESD (electrostatic discharge) protection is required.

  2. Load the string to a buffer in the SDM-SIO4, and issue the command to send the string. For details, see the SDM-SIO4 Instruction Manual.

  3. It depends. It is possible to connect serial sensors to a data logger without the use of an SDM-SIO4. However, if the sensors require hardware flow control or true RS-232 voltage levels, an SDM-SIO4 may be needed. The SDM-SIO1 also works with RS-485 signals and is a preferred alternative to the SDM-SIO4.

  4. Not the same, but similar. The SDM-SIO4 provides RS-232 voltage levels; the CR1000 control ports provide 0 to 5 V only. Both usually work with all sensors, and both devices are compatible with RS-232 and TTL logic. The CR1000 is easier to set up and program for serial input. The SDM-SIO1 is a preferred alternative to the SDM-SIO4.

    When compared to the CR10X, the CR1000 can handle strings as a specific data type. It also has more integrated serial interfaces including the following:

    • Four control port pairs—COM1 (C1 TX / C2 RX) through COM4 (C7 TX / C8 RX)
    • RS-232 port
    • CS I/O port for connection to CS I/O peripherals

    The serial I/O capabilities of the CR1000/CR3000 are similar to, and faster than, the SDM-SIO4 capabilities on a CR10X or CR23X. SDM devices are addressable and are connected to a data logger on C1 through C3. Therefore, one benefit of using multiple SDM devices on a CR1000 datalogger is that only three control ports are used.

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