The SDM-AO4 is a synchronous device for measurement (SDM) that provides four analog outputs. Values in the data logger are transferred to the SDM-AO4 as digital values. The SDM-AO4 then performs a digital-to-analog conversion and outputs an analog voltage signal.Read More
The SDM-AO4 provides four independent, continuous, analog outputs for proportional control or driving strip charts. Measured or processed values in the data logger are scaled to millivolts and transferred to the SDM-AO4 as digital values. The SDM-AO4 then performs a digital to analog conversion and outputs an analog voltage signal. The output voltage level is maintained until updated by the data logger.
The data logger enables individual modules through an addressing scheme; multiple SDMs (in any combination) can be connected to one data logger. After a module is enabled, it operates independently of the data logger until additional commands are received or results are transmitted.
|Analog Output Range||±5000 mV|
|Analog Output Resolution||2.5 mV|
|Output Resistance||200 ohm|
|Accuracy||±(0.5% of l Vout l +5 mV) for loads 75 kohm or greater|
|Operating Voltage||9.6 to 16 Vdc|
|Typical Current Drain||10.5 mA|
|Output Current||< 0.125 mA|
|Minimum Load||75000 ohm|
Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.
|CR3000 (retired)||SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.|
|CR5000 (retired)||SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.|
Up to 16 SDM devices can be connected to a single data logger.
The SDMAO4 Instruction controls the SDM-AO4 operation in CRBasic; Instruction 103 controls the SDM-AO4 operation in Edlog.
It is often convenient to power the SDM-AO4 from the data logger power supply, but when doing so consideration must be given to the SDM-AO4’s 10.5 mA continuous current drain. The alkaline supply available with the data logger has 7.5 Ahr and will power one SDM-AO4 for less than one month. This supply is not recommended for continuous long-term operation. The data logger’s sealed rechargeable power supply, float charged by an ac supply or solar panel, may be used for long-term operation.
The SDM-AO4 may also be powered from an external 12 V supply, independent from the data logger supply. The low side of an external 12 V supply should be connected to data logger ground and not directly to earth grounded.
The SDM-AO4 requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. SDM-AO4 serial numbers 2145 or higher have built-in keyhole flanges for mounting to the backplates of Campbell Scientific enclosures; the first unit to use these flanges was shipped in 18 September 1997. Grommets and screws are provided to attach the flanges/bracket to the backplate of our enclosures. Older SDM-AO4s required our 6279 SDM-AO4 Mounting Bracket (now retired) for this purpose.