Instruction manual

AM16/32 Relay Analog Multiplexer
6
RES CLK GND 12V
O
N
MUXPOWER
SHIELD
FIGURE 3. AM16/32 to Datalogger Power/Control Hookup
With the 21X or CR7 the AM16/32 connects to the 12VDC 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 AM16/32. A signal in the range
of +3.5 to +16VDC applied to the reset terminal activates the multiplexer.
When this line drops lower than +0.9VDC, 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. Instruction 86 (option code 41 -
48 to activate, and 51 - 58 to deactivate) is generally used to activate/deactivate
the multiplexer, however, in the case of the 21X or CR7 with older PROMS,
Instruction 20 is commonly used. The CR5000 and CR1000 uses the PortSet
instruction to control the reset line.
4.1.2 Clock
Pulsing the AM16/32 “CLK” line high (“RES” line already high) advances the
channel. When reset first goes high, the common terminals ODD H,
ODD L and EVEN H, EVEN L are disconnected from all sensor input
terminals. With the panel switch in “4X16” mode, when the first clock pulse
arrives the “COM” terminals are switched to connect with sensor input channel
1 (blue lettering) consisting of 1H, 1L, 2H, and 2L. When a second clock pulse
arrives the common lines are switched to connect to channel 2 (3H, 3L, 4H,
4L). The multiplexer advances on the leading edge of the positive going clock
pulse. The voltage level must fall below 1.5 VDC and then rise above 3.5 VDC
to clock the multiplexer. The CLK pulse should be at least 1 ms long. A delay
(typically 10 to 20 ms) is inserted between the beginning of the CLK pulse and
the measurement instruction to ensure sufficient settling time for relay contacts.
CR10X CR23X CR1000 CR5000 21X CR7
G
G
12 V 12 V 12 V 12 V +12 V 12 V
GGG G
C1-C8 C1-C8 C1-C8 C1-C8 EXCIT 1-4 EXCITATION
C1-C8 C1-C8 C1-C8 C1-C8 C1-C8 725 Card
Control