Instruction manual

ManualsBrandsCampbell ManualsComputer equipmentAM16

AM16/32 Relay Analog Multiplexer

A problem with making full bridge measurements with this

configuration is that the resistance of the lead wire and multiplexer

relays can cause a voltage drop, reducing the excitation at the bridge.

The following section describes a configuration that compensates for

this by measuring the excitation at the bridge.

6.5 Full Bridges with Excitation Compensation

Sensor to Multiplexer wiring – With panel switch set to ”4X16” mode

you are 2 lines short for a six wire measurement. One solution is to

multiplex the four signal wires through the AM16/32, but bypass the

AM16/32 with excitation and ground wires. This means that the

sensors will be excited in parallel which causes a higher current drain,

possibly enough to exceed the current available from the datalogger's

excitation channel. Alternatively, the excitation and ground leads can

be multiplexed through an additional AM16/32 allowing the sensors to

be excited one at a time (Figure 16). In this case the 12V, GND, CLK,

and RES lines of the second multiplexer are wired in parallel with

those of the first, effectively widening the multiplexer to “8X16”.

Multiplexer to Datalogger wiring - Four leads from the COM ODD,

EVEN terminals connect to two sequential differential analog channels

in the datalogger. Excitation and ground are multiplexed by the

second AM16/32. Both multiplexers can be reset and clocked by the

same control ports and/or excitation channels to simplify

programming.

21x

CR7

CR10(X)

"4 X 16" Mode

COM H (ODD)

COM L

COM H (EVEN)

COM L

ODD H

ODD L

EVEN H

EVEN L

SENSOR SHIELDS

COM

"4 X 16" Mode

E/VX

COM H (ODD)

COM L

ODD H

ODD L

CR23X/

CR5000

FIGURE 16. Full Bridge Measurement with Excitation Compensation

CR23X/

21X CR1000/

CR7 CR10(X)

CR5000