Campbell Hausfeld SDM-SIO4 SDM Port, Case, Power Requirements, Environmental Operating Range

SDM-SIO4 4-Channel Serial I/O Interface User Guide

1.2.2 SDM Port

This serial port is to connect to the SDM port of the datalogger, e.g. via C1, C2 and C3 on a CR10X. The port is a set of screw terminals marked C1, C2, C3, I/O, +12 and G. C3 is the Synchronous Device Enable line, C1 is the Data line, C2 is the Clock line and I/O is a special-purpose Interrupt line.

The Interrupt line can be used with some dataloggers to tell the datalogger to collect data from the sensor. The SDM-SIO4 pulses the I/O line for 50ms every 250ms if there is data available for the datalogger to collect. This can be used for sensors which send out data without prompting. For dataloggers which support interrupt-driven subroutines this can simplify program operation.

The SDM port is used by the datalogger to communicate with the SDM- SIO4 and other SDM peripherals. The speed at which data is transferred is under the control of the datalogger and this can vary with other activities in the datalogger and also the length of the SDM cables. The typical transfer speed to and from the SDM is one byte per millisecond.

Multiple SDM-SIO4s can be connected to the datalogger in parallel with other SDM-SIO4s or other SDM devices. The only difference would be the SDM address of each device.

NOTE For high speed communications the SDM cable should be kept as short as possible and connections made using screened cable. The cable between the SDM-SIO4 and the datalogger should not exceed 3m in length.

1.2.3 Case

The case is made of anodised aluminium. It has four slots for 9-way ‘D’ connectors and one slot for the SDM 6-way screw terminals. There is a momentary push-button switch for command line activation. The size of the case is 184 x 88 x 34mm. There is a tab at each end to allow for vertical mounting.

1.2.4 Power Requirements

The SDM-SIO4 has a typical quiescent current consumption of about 0.7mA. This increases to about 29mA with all 4 ports active. The quiescent state is entered if there has been no SDM or port activity for approximately 30ms.

The unit can be powered from an unregulated 12V supply (acceptable range 9 - 18V DC).

1.2.5 Environmental Operating Range

-25°C to +50°C (contact Campbell Scientific for extended temperature requirements)

0 - 95% RH (non-condensing)

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