Filter
Top Products
SDM-SIO4 4-Channel Serial I/O Interface User Guide
1-4
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.
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)
NOTE