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AM25T Solid-State Thermocouple Multiplexer 

4.3  Power (12V) 

The AM25T requires a 9.6 to 16 Vdc (12 Vdc nominal) power supply. 

In low current drain applications, it is convenient to power the AM25T from 

the data logger battery. For power intensive operations, use a high amp hour 

12 Vdc battery. 

See Campbell Scientific’s application note on power supplies 

(

https://s.campbellsci.com/documents/us/technical-papers/pow-sup.pdf

) for 

information on calculating the power requirements for a system. 

4.4  Power Ground (G), Ground Terminals (

Each differential input channel has a ground terminal located next to it. The 

ground terminals (

) are common with the power ground (G) and the ground 

lug on the base. Connect the sensor shields to the ground terminals (

). Always 

tie the data logger and multiplexer to a common earth ground via the ground 

lug. 

4.5  Analog Ground (

The analog ground terminal is the ground reference for the AM25T reference 

temperature measurement. It is the 

 terminal located between the 

VX

 and 

HI

 

terminals. Analog ground is not common with the other ground terminals 

labeled 

G

The analog ground terminal must be connected to the data 

logger ground as shown in TABLE 

7-1

.

 

4.6  Reset (RES) 

A control terminal is used to operate the 

RES

 channel. The AM25T is reset 

and activated by applying and holding 5 Vdc to the 

RES

 channel. Once the 

AM25T is activated, the AM25T reference temperature can be immediately 

measured. The AM25T enters its quiescent state when the 

RES

 channel is set 

to 

0

 Vdc.  

4.7  Clock (CLK) 

Pulsing the 

CLK

 channel sequentially advances the relays. A control terminal 

is used to operate the 

CLK

 channel. 

The first 

CLK

 pulse advances the relays to the reference temperature excitation 

channel. The second 

CLK

 pulse advances the relays and connects 

HI

 and 

LO

 to 

1H

 and 

1L

 on the multiplexer. 

Two clock pulses are required to advance to the next adjacent 

sensor input channel on the AM25T. 

The fourth 

CLK

 pulse advances the relays and connects 

HI

 and 

LO

 to 

2H

 and 

2L

. The sixth 

CLK

 pulse advance the relays and connects 

HI

 and 

LO

 to 

3H

 

and 

3L

. This sequence is continued for the remaining input channels. 

NOTE 

Содержание AM25T

Страница 1: ...AM25T Solid State Thermocouple Multiplexer Revision 1 19 Copyright 1995 2019 Campbell Scientific Inc...

Страница 2: ...ucts to CSI CSI will return such Products by surface carrier prepaid within the continental United States of America To all other locations CSI will return such Products best way CIP port of entry per...

Страница 3: ...ing address is CAMPBELL SCIENTIFIC INC RMA _____ 815 West 1800 North Logan Utah 84321 1784 For all returns the customer must fill out a Statement of Product Cleanliness and Decontamination form and co...

Страница 4: ...beginning work Wear a hardhat and eye protection and take other appropriate safety precautions while working on or around tripods and towers Do not climb tripods or towers at any time and prohibit cl...

Страница 5: ...nd G Ground Terminals 3 4 5 Analog Ground 3 4 6 Reset RES 3 4 7 Clock CLK 3 5 Terminal Strips 4 6 Specifications 5 7 Installation 6 7 1 Installing the AM25T 6 7 2 Data Logger to AM25T Wiring 7 7 3 Sen...

Страница 6: ...Terminal Strips 4 5 2 AM25T with Spring Loaded Terminals 5 7 1 External Battery Connections 7 7 2 Differential Measurement of Type T Thermocouple 9 7 3 Differential Voltage Measurement 9 8 1 Short Cu...

Страница 7: ...suitable for resistive bridge measurements high impedance of the solid state relays or multiplexing power 25 mA maximum switching current A maximum of 25 thermocouples differential voltage measurement...

Страница 8: ...ng material for product that may be concealed Check model number part numbers and product descriptions against the shipping documents Model or part numbers are found on each product On cables the numb...

Страница 9: ...rminal located between the VX and HI terminals Analog ground is not common with the other ground terminals labeled G The analog ground terminal must be connected to the data logger ground as shown in...

Страница 10: ...e length of the AM25T are for sensor connections All inputs are protected by spark gaps All terminals accept stripped and tinned wires up to AWG wire gauge 16 A strain relief flange is located between...

Страница 11: ...n tighten the screw 6 Specifications Power Unregulated 9 6 to 16 Vdc 12 Vdc nominal Current Drain Quiescent 0 5 mA Active 1 0 mA typical Enable Inactive 0 9 V Active 3 5 to 5 0 V 7 V max Clock The rel...

Страница 12: ...0 Maximum Switching Current 25 mA switching currents greater than 25 mA damages the relays and renders them unusable Compliance View the EU Declaration of Conformity at www campbellsci com am25t Assum...

Страница 13: ...te battery might be used when the AM25T is installed some distance from the data logger Ground must be connected between the data logger and the AM25T FIGURE 7 1 FIGURE 7 1 External Battery Connection...

Страница 14: ...rence PRT is located in the AM25T This reference temperature does not require an additional data logger input to measure the reference Thermal gradients between the AM25T sensor input terminals and th...

Страница 15: ...nsor Types Different sensors may be mixed on the AM25T Additional loops and measurement instructions will be required 8 Operation 8 1 General Measurement Considerations Wires have additional capacitan...

Страница 16: ...many program configurations for various supported sensors providing a quick way to generate a program and wiring diagram FIGURE 8 1 Short Cut can be downloaded free of charge www campbellsci com FIGU...

Страница 17: ...ntrol the AM25T multiplexer with the data logger The instruction measures the PRT incorporated in the AM25T and uses it as a reference temperature for thermocouple measurements The AM25T instruction a...

Страница 18: ...g the procedure in Section 4 Overview p 2 Finish the program On the Advanced tab click the CRBasic Editor button The program opens in CRBasic with the name noname CR_ Provide a name and save the progr...

Страница 19: ...Common High HI U5 Common Low LO U6 1 Analog Ground is the terminal located between the VX and HI terminals on the AM25T CRBasic Example B 1 CR6 Program Using One Instruction to Measure Both the Refere...

Страница 20: ...Battery BattV Default CR6 Datalogger Wiring Panel Temperature measurement PTemp_C PanelTemp PTemp_C 60 Type T copper constantan Thermocouple measurements Temp_C on the AM25T Multiplexer AM25T Temp_C 2...

Страница 21: ...Asia Location Bangkok Thailand Email info campbellsci asia Website www campbellsci asia China Location Beijing P R China Email info campbellsci com cn Website www campbellsci com cn Spain Location Ba...

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