Hi There
I hope u can help me.
I am using a CR1000 with a AM1632 Multiplexer.
At the moment i have 18 10HS Moisture sensors connected to the multiplexer...
MY Wiring Diagram
LOGGER AM1632
1H -> COMM ODD L
1L -> COMM EVEN H
2H -> COMM EVEN L
SW-12 -> COMM ODD H
C1 -> RES
C2 -> CLK
My program below:
'Declare Variables and Units
Dim LCount_4
Public BattV
Public Sensor(18)
Public Thermocouple1
Public Thermocouple2
Public PTemp
'Define Data Tables
DataTable(HourlyData,True,-1)
DataInterval(0,60,Min,10)
Average (1,Ptemp,FP2,False)
Average(1,BattV,FP2,False)
Average (18,Sensor,FP2,False)
EndTable
'Main Program
BeginProg
Scan(15,Sec,1,0)
'Default Datalogger Battery Voltage measurement BattV
Battery(BattV)
PanelTemp (PTemp,250)
'Turn AM16/32 Multiplexer On
PortSet(9,1)
PortSet(1,1)
Delay(0,150,mSec)
LCount_4=1
SubScan(0,uSec,10)
'Switch to next AM16/32 Multiplexer channel
PulsePort(2,10000)
'Generic Single Ended Voltage measurements TenHsmV() on the AM16/32 Multiplexer:
VoltSE(Sensor(LCount_4),3,mV2500,1,True,0,_60Hz,1,0)
LCount_4=LCount_4+3
NextSubScan
For LCount_4=1 To 30
Next
'Turn AM16/32 Multiplexer Off
PortSet(1,0)
PortSet(9,0)
Delay(0,150,mSec)
'Call Data Tables and Store Data
CallTable(HourlyData)
NextScan
EndProg
My problem is I need to add about 5 Thermocouples to my program and I'm not sure how to add it.. The 10HS Sensors are working fine... Can someone help me please!!!
Thanks
Public Thermo(5)
'Thermocouples to CR1000
'Therm 1 -> Diff 4
'Therm 2 -> Diff 5
'Therm 3 -> Diff 6
'Therm 4 -> Diff 7
'Therm 5 -> Diff 8
TCDiff (Thermo(),5,mV2_5C,4,TypeT,PTemp,True ,0,250,1.0,0)
Hi Thanks for your reply, but I need to connect the thermocuples to the multiplexer not logger due to the logger been very far away from the multiplexer and i would need very long thermocouples.
Thermocouples need a reference temperature like the thermistor in the CR1000 wiring panel or in the AM25T. You need to look at acquiring a AM25T (http://www.campbellsci.com/am25t)
Hi Sam
Right now i dont have a budget to buy the AM25T and i have to make do with the current set up.
Cant i make up a thermister with a thermocouple. I've read of this before where a piece of foam or polystyrene is insulated around the end of the thermocouple and used as a thermister or the other scenario - I could attach one extra long thermocouple to logger and place it on the multiplexer cover and use that as Ref Temp.
Is that possible. I dont need precise readings from thermocouples so if there is errors within a reasonable amount it will be exceptable.
I'll still need help to ammend my program though!
Thanks
A thermistor and a thermocouple are two completely different types of sensors. They rely on different physical properties of materials. You can not turn one into another. You need a known temperature reference for thermocouple measurements (in lieu of having a true cold junction)
Note - you are cutting corners that will lead to sub-par measurements. Keep that in mind.
In a pinch you could try
1) Connecting the multiplexer COM terminals to the logger using a length of the same thermocouple wire you are using to take the measurements. It is important to use the same type of TC wire.
2) Reading a thermistor connected at the multiplexer.
3) As you mentioned, thermocouple from logger to multiplexer and use it as a Ref Temp.
Make sure you use the insulating cover for the multiplexer and logger.
You will need to amend your program to control a multiplexer and take the TCDiff measurements. ShortCut can be used to generate an example program to start with (Devices->AM16/32->Type X Thermocouple).
* Last updated by: Sam on 6/1/2011 @ 10:29 PM *
Hi Sam
After mush thinking i decided to move the logger into the same enclosure as the multi plexer and connecting the thermocuples directly to it as you said above
Public Thermo(5)
'Thermocouples to CR1000
'Therm 1 -> Diff 4
'Therm 2 -> Diff 5
'Therm 3 -> Diff 6
'Therm 4 -> Diff 7
'Therm 5 -> Diff 8
TCDiff (Thermo(),5,mV2_5C,4,TypeT,PTemp,True ,0,250,1.0,0)
This elimanted much problems and all i needed to do was to put in a long cable with RS232 connections either side so it can be connected to the pc,
Thanks for all your assistance!!
An what about a difference temperature between two linked thermocouples.
I have two thermocouples with two junction: Cu-(T1)-Cst-(T2)-Cu. If I wire the two Cu cables on the datalogger (1H and 1L), I will monitor the difference of temperature between the two thermocouple junctions (difference between T1 and T2).
But I think I need to force the TempRef to zero in the TCDiff command instead of using the PTemp?