SDM-CD16S 16-Channel Solid-State DC Controller
Expands Datalogger Control Capacity
For DC devices with
higher current loads
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The SDM-CD16S adds capability to a datalogger by controlling DC devices that have a relatively high-powered load, such as solenoids, solenoid valves, DC motors, stepper motors, lights, horns, heaters, and fans.

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Benefits and Features

  • Allows the data logger to automatically turn devices on or off when a threshold (for example, temperature or water depth) has been reached
  • Provides a manual override
  • Includes LEDs for a visual indicator of active outputs
  • Drives up to 100 W of power on each channel


Technical Description

This relay driver provides 16 DC voltage outputs that can be switched on and off manually or under datalogger control. The SDM-CD16S's toggle switch has three positions: MANUAL, OFF and AUTO. In the MANUAL position, outputs are controlled by the position of the individual rocker switches. In the OFF position, all outputs are off. In the AUTO position, the state of the relays is controlled by the SDM commands from the datalogger or by the logic control inputs.

Separate inputs for power-to-outputs (48 Vdc maximum) and power-to-SDM-CD16S logic (7 to 48 Vdc) allow the option of powering the logic from the datalogger’s 12 V while switching a higher voltage.

With a voltage range of up to 48 Vdc and a maximum current output per channel of 2 A, the SDM-CD16S can drive up to 100 W of power on each channel.

SDM Operation

The SDM-CD16S is a synchronously addressed datalogger peripheral. Datalogger control ports 1, 2, and 3 are used to address the SDM-CD16S, then clock out the desired state of each of the 8 control ports. Up to 15 SDM-CD16S devices may be addressed, making it possible to control a maximum of 256 ports from the first three datalogger control ports.

Datalogger Connection

The CABLE5CBL-L is recommended for connecting the module to the datalogger. A 1-ft cable length should be sufficient when both datalogger and SDM-CD16S are housed within an ENC12/14 enclosure; a 2-ft length may be required if the datalogger and SDM-CD16S are housed at opposite ends of an ENC16/18 Enclosure. The cable length should be as short as possible. Typically, the maximum cable length is 20 ft. Contact Campbell Scientific if the length needs to be longer.


Function Allows the data logger to control dc devices that have a relatively high-powered load, such as solenoids, solenoid valves, dc motors, stepper motors, lights, horns, heaters, and fans.
Number of Channels 16
Isolation Optically isolated between the inputs and outputs
Logic Power Voltage 7 to 48 Vdc
Logic Current Drain (@ 12 Vdc)
  • 15 mA quiescent
  • 2.5 mA per active LED (manual or auto)
Toggle Switch
  • Individual dip switches for manual
Supply Voltage for Output 48 V max (dc only)
Operating Voltage 12 Vdc
Maximum Current
  • 2 A (per channel)
  • 10 A fused (all channels total)
Fuse 3 AG 10 A
Actuation/Release Times 8 μs/200 μs
Operating Temperature -40° to +70°C
Maximum Cable Length 6 m (20 ft) total to all SDM devices
(Contact Campbell Scientific if longer lengths are necessary.)
Dimensions 24.1 x 12.7 x 6.4 cm (9.5 x 5.0 x 2.5 in.)
Weight 771.1 g (1.7 lb)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR3000 For the CR3000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR5000 (retired) For the CR5000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR800 (retired)
CR850 (retired)
CR9000X (retired)

Mounting Equipment

Product Compatible Note


Product Compatible Note

Additional Compatibility Information

Enclosure Considerations

The SDM-CD16S requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. Grommets and screws are provided to attach the flanges/bracket to the backplate of our enclosures.

Power Considerations

The SDM-CD16S power requirements may be large compared to most Campbell Scientific products. For most applications, an external power supply is recommended to power the SDM-CD16S.

For some applications, it may be convenient to use the data logger’s sealed-rechargeable battery. If the data logger’s rechargeable batteries are used, the batteries need to be float charged via a wall charger or solar panel. The current available from the wall charger limits the SDM continuous output current. Campbell Scientific does not recommend using the data logger’s alkaline power supply.

FAQs for

Number of FAQs related to SDM-CD16S: 5

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  1. No. The SDM-CD16S was designed to switch dc loads (7 to 48 Vdc; 2 A maximum per channel). The load power is isolated from the logic power (12 Vdc).

    To switch an ac load, consider using an SDM-CD16ACA.

  2. The SDM-CD8S and SDM-CD16S were specifically designed to switch solenoids (inductive loads), similar to those found on valves. The diode, to protect against voltage kickback, is built into the device. The SDM-CD16AC, however, does not have this diode.

  3. Yes. Each of the channels on the SDM-CD8S and the SDM-CD16S has a manual control switch. Place the SDM-CD8S or SDM-CD16S into manual control by switching the Manual Control switch to the On position. Now each channel can be turned on or off using its respective switch.

  4. The following relay devices can be used with the CR800 and the CR850:

    • 7321
    • A6REL-12*
    • A21REL-12
    • LR4
    • SDM-CD8S
    • SDM-CD16AC
    • SDM-CD16ACA
    • SDM-CD16S

    The CR800 and the CR850 can also be used with a wide variety of third-party relay devices.

    *Because the CR800 and the CR850 only have four digital ports, they do not have the ability to switch all six of the relays on the A6REL-12.

  5. Yes. SDM devices are addressable. Multiple SDM devices can be connected to a data logger, as long as they all have a unique SDM address. Valid addresses are 0 through 15. Address 16 is reserved for SDM devices that support the Group Trigger Command. The address is set using the rotary switch on the face of the SDM-CD8S or SDM-CD16S.

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