Campbell Scientific SDM-IO16 16-Channel Input/Output Expansion Module - Manual (Page 11)

SDM-IO16 16 Channel Input/Output Expansion Module
OV
From sensor
510 Ω 33 Ω
5 V
100 K
To internal logic
5.6 V
O V
a) Input biasing and protection
0.6 V Drop
Output
Output
550 Ω
b) Output set ON c) Output set OFF
510 Ω
V 5 V, 0 Ω
0.33 Ω
FIGURE 2. Simplified Equivalent Port Circuits
3. Power Considerations
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.
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