Power Considerations - Campbell SDM-IO16 User Manual

SDM-IO16 16 Channel Input/Output Expansion Module
To internal logic
0.6 V Drop
0.510 
5 V, 0
V
b) Output set ON

3. Power Considerations

4
Accuracy:
Duty cycle resolution:
Max measurement interval: for frequency or duty cycle measurements the
1
If more detailed input/output characteristics are required, experienced users
should consult the equivalent circuit diagrams shown in Figure 2.
2
See Appendix B for a more detailed discussion of switch debounce, resolution
and accuracy.
5 V
0.510 
5.6 V
OV
0 V
a) Input biasing and protection
33 
.Output
Figure 2. Simplified Equivalent Port Circuits
For most applications, especially for pulse counting or status inputs, it is more
normal to use the datalogger supply to power the SDM-IO16, as shown in Figure
3(a).
When being used for control and outputting current the SDM-IO16 power
requirements can be large compared to most Campbell Scientific products when
driving significant loads. For this type of application an external power supply, as
shown in Figure 3(b), is recommended to power the SDM-IO16.
internal clock accuracy 0.01% (worst case) over
the standard temperature range of -25 to +50C.
See also Appendix B for a discussion on
frequency resolution.
this depends on frequency and measurement
interval - See Appendix B. The average duty cycle
can be measured for signals up to 4 kHz.
datalogger must request a measurement at an
interval no longer than 15.9375 seconds. Each
channel can be measured at different intervals,
both for frequency and duty cycle.
100 K
0.33 
.From sensor
.550 
c) Output set OFF
.Output