The SDM-AO4 is a synchronous device for measurement (SDM) that provides four analog outputs. Values in the datalogger 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 datalogger 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 datalogger.
The datalogger enables individual modules through an addressing scheme; multiple SDMs (in any combination) 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.
|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|
Up to 16 SDM devices can be connected to a single datalogger.
The SDMAO4 Instruction controls the SDM-AO4 operation in CRBasic; Instruction 103 controls the SDM-AO4 operation in Edlog.
*For the CR3000 and CR5000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
**The CR7X requires a CR700X module ordered after 1 Sept 1996 or upgraded to include a CR700X CPU module.
It is often convenient to power the SDM-AO4 from the datalogger 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 datalogger 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 datalogger’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 datalogger supply. The low side of an external 12 V supply should be connected to datalogger 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.