Campbell AM416 Instruction Manual - page 10
AM416 RELAY MULTIPLEXER
4
FIGURE 2. Hook-up Diagrams for Datalogger - AM416 Connections
CR10(X) Hook-up 21X Hook-up
CR7 Hook-up
The 21X or CR7 (with a 725 Card) can be used
to connect 12VDC supply and ground to the
AM416. One control port is used for reset, and
one switched excitation channel is used for
clock. If switched excitations are unavailable, a
control port may be used to provide clock
pulses to the multiplexer.
4.1.1 RESET
Reset (RES) controls activation of the
multiplexer. A voltage (3.5VDC 16VDC) applied to this terminal activates the multiplexer. When this line is dropped to <0.9VDC, the multiplexer enters a quiescent, low current drain state. Reset is always connected to a datalogger control port. Instruction 86 (option code 41 - 48 [activate] and 51 - 58 [deactivate]) is generally used. With a 21X or CR7 with older PROMS, Instruction 20 is commonly used to activate and deactivate the multiplexer (set port high to activate the multiplexer or low to enter quiescent mode). 4.1.2 CLOCK The multiplexer clock line (CLK) controls the switching between sequential sets of relays. When reset is set high and the multiplexer is activated, the multiplexer's common lines (COM H1, COM L1 COM H2, COM L2) are not connected to any of the sensor input terminals. When the first clock pulse is received, the common lines are switched into connection with multiplexer channel 1 (H1,L1,H2,L2). When a second clock pulse is received, the common lines are connected to multiplexer channel 2 (H1,L1,H2,L2). Adjacent Multiplexer input channels are momentarily shorted to each other during the switch (e.g. channel 1 H1 to channel 2 H1, channel 1 L1 to channel 2 L1, etc. See Cautionary Notes). The multiplexer is clocked on the leading edge of the voltage pulse. The