In general the paper pad material for the AP4 calibration plate is not critical.

Filter or blotting paper is good. It is absorbent and will not contaminate the water used. Make sure it is a paper-based filter, not plastic. The finer the fibres in the paper the more water it will hold and the longer it will last before becoming dry.

We currently use blotting pads 32x60mm in size from a company called Moreton Hall Press. P/N: DEL26084

Logger Relay Limits: The number of items powered though a logger relay (DL2e or DL3000) is limited by the DC and surge currents. The logger relays can each switch 2A DC or about 5A for a brief surge of a few ms.    
    
ITEMS LIMITED; Max number of items per Relay; Notes

M20 Modem; 1; Limit from 2A transmit peak
ML1 ThetaProbe; 11; Inrush surge limited
EQ1 Equitensiometer; 11; Inrush surge limited
ML2 ThetaProbe; 16; Inrush surge limited
ML2x ThetaProbe; 16; Inrush surge limited
SM200; 16; Inrush surge limited
EQ2 Equitensiometer; 16; Inrush surge limited
PR1/6 Profile Probe; 8; From DC limit (PR2 is the same)
PR1/4 Profile Probe; 12; From DC limit (PR2 is the same)
TVB1 Voltage Regul'r; 1; Inrush surge limited
TVB1 Voltage Regul'r; 2; From TVB1 s/no 930
VP1 Psychrometer; 1; Motor stall limit

ITEM LIMITS not normally a problem:   
ACS1; AC excit'n Source; 21 
AN3; Anemometer; 18 
BS4; Barometer; 125 
ML2x; Thetaprobe; 50; ??After s/no.102-25 May 2001
EQ2; Equitensiometer; 50; ??Based on above ML2x 
RHA1; RH; Sensor; 500  
RHT2; RH Sensor; 50 
SWS; Surface Wetness Sensor; 200 
    
TO CALCULATE LIMITS for mixtures of items on one relay: 
The sum of (number of items/per Relay) for all items must be <1.    
eg: 8xML1 and 2xPR1/6 on one relay is just ok, because 
(8/11) + (2/8) = 0.98    
    
SLAVE RELAY 
If you must switch higher currents use an external relay, with high current contacts. 
Power this slave relay's coil from the Logger relay. 
??For example, on "12V"-powered Loggers a relay with 10A DC, ??nnA surge contacts would enable 5x the number of logger-relay powered items, shown above. 

Problem

The GP1 works fine when communicating with a standard connection but when setting it up as a network connection (typing in the serial number and checking the network tick box) the unit fails to communicate with DeltaLINK and the error ‘no reply from logger’ is displayed.
 This problem is to do with the GP1 serial number fields sometimes being corrupted.

It applies to:
• GP1 when used in a network
• WS-GP1 when used in a network

Solution

We have created a software tool that can be downloaded from our website. When run, this will automatically fix the serial number problem and network functionality will be restored.

Requirements

DeltaLINK 2.3.1 installed
Serial port to connect to logger with.

How to use the software
1) Connect logger to serial port.
2) Using DeltaLINK
a) Stop logging.
b) Save data if required.
c) Erase complete dataset.
d) Close DeltaLINK.
3) Run DeltaLINK Serial Number Patch tool.
4) Select COM port, or type in if not shown.

Site factors: In general, site factors assume you are measuring radiation on a horizontal surface ( ie radiation measured using properly levelled cosine-corrected sensors) so you should make no adjustment for this.

However, there may be circumstances when you want to look at radiation load on the canopy floor, when it is appropriate to take account of the slope. You can do this by changing the Intercepting Surface settings. The values you have to enter are the Azimuth and Zenith angles of the perpendicular to your surface.

The Azimuth angle is the angle from North (via East) of the steepest downwards slope.

The Zenith angle is the same as the maximum angle between your slope surface and horizontal.

Select a single sided surface (double sided is only appropriate to single leaves that receive radiation from both sides).
Your values of radiation above and below will now be the same as if you measured them with a cosine corrected sensor in the plane of your surface.

Is the RS232 cable correctly fitted between the PC and HH2? Check that the cable connectors fit tightly. There may be problems with the 9-25 D adaptor at the HH2 end. You may have to try swapping with other cables or adaptors.

Are you using the right COM port? Check which serial port is used on the PC. Check that the HH2Read software is set to use that COM port. If a USB to RS232 convertor is being used, please check which COM port has been assigned to it in the device manager (see FAQ 44).

Have you got the right type of RS232 cable? (Delta-T Sales Code HHRS2). The normal RS232 cable has female connectors at each end (and has crossed over lines between some pins). Do not confuse these with RS232 modem cables. Modem cables have male and female connectors (and are wired straight through).

Make sure the HH2 is switched off when communication is attempted

Check what version of HH2read is being used (open HH2 read, click on help, about) and what version of HH2 firmware they are using (switch on the HH2, pres set, scroll to status, press set, scroll to versions, press set, scroll down to see what version the firmware is. It may be that the HH2read softwaremay need updating to the latest version (this can be downloaded from our website, the customer may need to uninstall the current version though – check the readme documents that accompany the installation)

We have noticed that some modern PC's immediately wake the HH2 when they are connected to the PC. Sometimes they are then unable to communicate with the HH2, or communicate inconsistently. The PC's that suffer the problem are different brands (Dell Dimension and Compaq) running Windows 2000. However, other Windows 2000 PC's don't suffer the same problem.

Action

The PC software HH2Read v2 (released March 2002) should improve this situation. But if the problem is encountered, users should be advised not to connect their HH2 before starting HH2Read, and to disconnect it before closing HH2Read.

Note also that if the HH2 is left connected to the closed serial port, it is unable to sleep, and reports that a powered sensor is unexpectedly connected. Disconnect the HH2 from the PC.

BACKGROUND INFORMATION
HH2Read v2 manages the serial port differently from earlier versions, by keeping the serial port open. Earlier versions of HH2Read close the serial port between messages, causing unexpected -9V to +9V transitions, which get confused with the transmitted data and normal communication is then disrupted.

When installing access tubes, air gaps between the outside of the tube and the soil must be minimised for accurate readings.

The most important thing you can do to ensure accurate readings from the Profile Probe is to minimise air gaps around the access tube.  Be careful when augering holes not to create a funnel-shaped hole by waggling the top of the auger, and be prepared to start again if you encounter avoidable stones or roots.

Air gaps can create serious errors in the readings. The Profile Probe is sensitive to the water content of the soil around its pairs of stainless steel rings.  This sensitivity is biased towards the soil closest to the rings.  Air gaps immediately around the access tube reduce the accuracy of the reading in two ways - firstly the sensors will measure some air instead of moist soil, but also the air gap reduces the penetration of the electromagnetic field into the surrounding soil.

It is virtually impossible to quantify the magnitude of errors from air gaps.

If air gaps are suspected, they can sometimes be diagnosed if the soil moisture content at a particular depth is anomalously low. Also, the reading at that depth may show a diminished range of variation in time, in relation to a known wetting event. However, if saturation and flooding of the soil around the tube occurs, the water content signal may exceed that at neighbouring depths.

After installation of the access tube, air gaps might be expected to close up with natural settlement of the loosened soil. However it is not easy to say how soon, or to what extent, this may occur.

WinDIAS creates data files (*.ds_) that are text files with spaces between the fields. You can open data files created by WinDIAS, in Excel, as follows.

1. Locate the folder with the file you want to process, in Windows Explorer.

2. Then run Excel, and "Open" the file.

3. If the Open file dialog box doesn't show the file in the folder, specify "all files" in the "Files of Type" box.

4. You should then get a "Text Import Wizard" for dealing with the particulars of the text format.

5. You can get reasonable results with either:

a)  "Delimited" (specify space, treat multiple spaces as one, text qualifier none), or

b) "Fixed width" (just choose where to make the columns).