Campbell AM16/32B, Руководство по эксплуатации продукта

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AM16/32B Relay Multiplexer 15
The average power required to operate an AM16/32B depends on the percentage of time it is
active. At a minimum, the power supply must be able to sustain the system between site visits
anticipating the worst environmental extremes. Refer to the application note Power Supplies and
the video Power Budgeting , both available at www.campbellsci.com , for more help in selecting a
power supply.
7.4 Installation in enclosure
Protect the AM16/32B from moisture. Moisture in the electronics will seriously damage the
AM16/32B. In most cases, protection from water is easily accomplished by placing the AM16/32B
in a weathertight enclosure with desiccant and elevating the enclosure above the ground.
Desiccant in enclosures should be changed periodically. Use a humidity indicator card inside the
enclosure to determine when the desiccant needs to be replaced.
Mount the AM16/32B to an enclosure backplate by inserting the included screws through the
mounting holes in the AM16/32B and into the included grommets.
8. Operation
The reset (RES) line is used to switch on the AM16/32B by applying 3.3 to 8 VDC. When this line
drops lower than 0.9 VDC, the multiplexer enters a low-power, low current-drain state. In the low-
power state, the common (COM) terminals are electrically disconnected from all the sensor input
channels. Always connect RES to a data logger terminal configured for control.
The
MuxSelect()
instruction is used to turn on the AM16/32B and advance to the channel
specified in the instruction. When the instruction is first given, the COM terminals are switched to
connect with the first set of measurement terminals according to the mode switch, either 4x16 or
2x32. Measurement instructions run within a
SubScan()
/
NextSubScan
construct.
PulsePort()
at the end of the SubScan switches (or clocks) to the next set of measurement
terminals by sending a pulse on CLK. The voltage level must fall below 1.5 VDC and then rise
above 3.3 VDC to clock the multiplexer.
Once the measurements are complete,
PortSet()
returns the AM16/32B to a low-power state.
Example programs using the
MuxSelect()
instruction are found in Example measurements and
programs (p. 21).
Another method of operation uses the
PortSet()
instruction in place of
MuxSelect()
.
Typically, this is seen when creating the program in
Short Cut or migrating a program from the
older AM16/32 or AM16/32A multiplexers. The program created in QuickStart (p. 3) uses the
PortSet()
instruction.
The terminals for sensor attachment are divided into 16 groups (mode switch set to 4x16) or into
32 groups (mode switch set to 2x32). The groups consist of four or two Simultaneously Enabled