Campbell Scientific AM16/32B Relay Multiplexer - Manual (Page 16)

AM16/32B Relay Multiplexer
dataloggers connect to the AM16/32B as shown in FIGURE 4-1 (“4x16”
mode). FIGURE 4-1 depicts control connections. Measurement connections
are discussed in Section 6, Sensor Hookup and Measurement Examples. The
power, ground, reset, and clock connections remain essentially the same
regardless of datalogger used.
With the CR5000, CR3000, CR800, CR850, CR1000, CR23X, and CR10(X),
the datalogger 12 Vdc supply and ground terminals are connected to the
AM16/32B 12V and ground terminals. One control port is required for
clocking and a second control port for reset. The cable’s shield is grounded on
both ends as illustrated in FIGURE 4-1.
RES CLK GND 12V
O
N
MUXPOWER
SHIELD
CR800,
CR850
CR10X,
CR3000,
CR1000
CR23X,
CR5000
21X CR7
G G
FIGURE 4-1. AM16/32B to datalogger power/control hookup using
CABLE4CBL cable
With the 21X or CR7, the AM16/32B connects to the 12 Vdc and “ ”
terminals for power. One control port is used for reset, and one switched
excitation channel is used for clock (on 725 card with CR7). If a switched
excitation port is not available, an additional control port can be used to
provide clock pulses to the multiplexer.
4.1.1 Reset
The reset (“RES”) line is used to activate the AM16/32B. A signal in the range
of +3.3 to +8 Vdc applied to the reset terminal activates the multiplexer. When
this line drops lower than +0.9 Vdc, the multiplexer enters a quiescent, low-
current-drain state. In the quiescent state, the common (COM) terminals are
electrically disconnected from all of the sensor input channels. Reset should
always connect to a datalogger control port. The CR800, CR850, CR3000,
CR5000, and CR1000 use the PortSet() instruction to control the reset line.
Instruction Do (P86) (option code 41 – 48 to activate, and 51 – 58 to
deactivate) is generally used to activate/deactivate the multiplexer when using
an Edlog datalogger; however, in the case of the 21X or CR7 with older
PROMS, instruction Set Port (P20) is commonly used.
12 V 12 V 12 V
CABLE
+12 V 12 V
G G G
C1-C4 C1-C8 C1-C8 EXCIT 1-4 EXCITATION
C1-C4 C1-C8 C1-C8 C1-C8 725 Card
Control
6