Campbell Scientific AM16/32B Relay Multiplexer - Manual (Page 19)

AM16/32B Relay Multiplexer
' ***** ' "Jump" AM16/32B directly to Channel 6
Scan (100,mSec,0,1)
PortSet(5,1) 'Raise Reset line
Delay (0,5,mSec) 'Keep reset HI for 5 ms
PortSet(5,0) 'Reset line set LO (enters "B Addressing" mode)
Delay (0,3,mSec)
For i = 1 To 6
'Pulse CLK line 6 times - addresses Channel 6
PortSet(6,1) 'Raise CLK
Delay (0,10,mSec)
PortSet(6,0)
'Drop CLK
Delay (0,10,mSec)
Next i
Delay (0,5,mSec)
PortSet(5,1) 'Raise Reset - selects Channel 6 (relays make contact)
NextScan
4.1
he AM16/32B has a ground lug that should be connected to earth ground via
an 8 AWG wire. This connection should be as short as possible. The ground
lug provides a path to dissipate surges that might propagate on a sensor’s shield
line. An 8-V, bi-polar transzorb connects shield ground to the ground lug.
separate power supply is used, the AM16/32B ground should also connect to
.3 Ground
T
The AM16/32B “GND” terminal is connected to datalogger power ground.
The AM16/32B “GND” terminal is also connected to the CABLE4CBL’s
SHIELD and, via that, to datalogger power ground (see FIGURE 4-1). If a
the separate supply’s ground (FIGURE 4-3). An AM16/32B COM terminal
should connect to a datalogger ground terminal (“ ” or “G”) via the cable
that connects the COM terminals (see Section
u
4.1.4 Power Supp
uous 12 Vdc power supply for operation. The
multiplexer’s current drain is less than 210 microamps in the quiescent state
is typically 6 to 11 milliamps at 12 Vdc when active (see current drain
). The power supply is connected to the multiplexer terminals labeled
supplies are
recommended where solar or AC charging sources are available because they
line
e the
4.2.1, COM Terminals, and
FIGURE 4-4). The datalogger must connect to earth ground by one of the
methods described in the installation and maintenance section of yo r
datalogger operator’s manual.
ly
The AM16/32B requires a contin
and
spec
“12V” (+) and “GND”. Connect the “GND” wire first for safety.
In many applications, it is convenient to power the AM16/32B from a
datalogger battery. For more power-intensive applications, an external,
rechargeable, 12 Vdc, 60 A h source may be advisable. Lead-acid
handle well being “topped off” by constant charging. The BPALK alka
supply (12 A h) can be used to power the AM16/32B in applications wher
average system current is low, or where it is convenient to frequently replace
batteries. It is advisable to calculate the total power requirements of a system
and the expected longevity of the power supply based on average system
current drains (for example, datalogger, multiplexer, other peripherals, and
sensors) at the expected ambient temperatures.
9