Procedure (≈30 minutes)

(Daily Calibration Check Procedure)


Software Sources

If you do not have Visual Basic installed on your computer let us know, we should probably send you an installation CD.
If you do, have Visual Basic installed, or if you feel confident enough you can download our software: CalibrationCheck.exe or its September,2006 version: CalibrationCheck9-06.exe
We recommend that you also download this typical "Defaults" file to get you started PathwayCalCheckDFT.txt. Just place it in the same folder as the application "CalibrationCheck.exe".
If you do not have Visual Basic installed on your computer and are not using the installation CD, you will also probably need to download the files listed below and paste them into your WINDOWS/System32 folder.
To register these files into your registry you can find some help on the web at sites such as:


The system consists of the Pathway calibration hardware supplied by Medoc: a YSI 4600 precision thermometer (with an RS232 serial port) and a thermode holder for both the ATS and CHEPS thermodes.
A standard  RS232 serial cable to connect the YSI 4600 to the computer (straight 9 pin D male to female).
A two conductor cable (coaxial) to connect the Pathway "TTL Out" front panel BNC to the "Acknowledge", pin 10 of a parallel (alias LPT, alias Printer) port. This TTL signal, from the Pathway software, indicates to the "Calibration Checker" when the test starts and when the end of a temperature plateau has been reached and it is time to record the temperature.


Main Window     If the YSI 4600 is connected to COM:1 and the Pathway  TTL is connected to LPT1 (with address 378Hex) of your PC, then the software should work as is.
    The window on the left is the only window with which a normal user should have to be concerned. For this reason, the menu "View"  tab is normally grayed out to avoid accidental changes to the setup. It can be made accessible by typing the word "options" while the main window has focus.

Menu View/COM Port

Serial Port Window     This window  permits selection of the com port to which the thermometer is connected. The software checks for the availability of the port, but not whether the thermometer is actually connected to it. This is the user's responsibility.
    When the YSI 4600 is properly connected to the RS232/COM port an "H" should appear on its LED display.
    When it receives a "T" command it should start sending its temperature readings  These readings should appear in the blue label entitled "RS 232 Data In".
    The software saves all the settings to a defaults file named "PathwayCalCheckDFT.txt" located in the application folder (the folder in which the Pathway Calibration Check software is located). Next time you start the software from the same folder, it will start with the same settings.
Calibration Checker Options (September, 2006)

Menu View/Options

This window  permits specifying:
1 -- The number of test points that are to be recorded for each, the ATS and the CHEPS thermodes.
2 -- The precision used for the pass/fail test (±0.20°C for the ATS and ±0.40°C for the CHEPS in the example).
3 -- An offset to the precision (added  for more flexibility but has never been used).
4 -- The BUS address of the parallel port to which the Pathway "TTL Out" BNC is connected.  378 hex, 3BC hex and 278 hex are the most common addresses.
5 -- The trigger source as the Pathway "TTL Out" BNC. Normally this box must be checked, but, if not checked, the keyboard space bar can be used as trigger to test the calibration check software without using the Pathway software.
6 -- Whether you want to save the temperature graph. This option is not used for calibration checks but was added to investigate instability/drifting of the temperature experienced with the CHEPS thermode.



The Pathway must be programmed to send a "TTL Out" pulse at the "Onset" of the first step to be recorded ( "Sequence #1" in the example), and at the "End of Duration" for every temperature to be checked (See Pathway ATS Program)  (See Pathway CHEPS Program) .
The TTL pulse should be set for positive going 1000msec pulse in the  Pathway menu "Settings / Hardware settings" (See Pathway Hardware Settings)
The Calibration Check window "Target" values must correspond exactly in number and amplitude to those in the Pathway program. There is no communication between the two programs; they can actually run off different computers but their programs must match. Notice that, starting March 30, 2006, the CHEPS program starts at 44°C, then goes down to 43°C and back up to 45°C.  Make sure the Calibration Checker is set the same way.  This change was made when the CHEPS failure to pass the calibration check was attributed to a foam warming up problem.  It is not clear at this time whether this was a necessary change.


See: OPPERA Pathway Daily Calibration Check Procedure.

Simulated Results

Main window (JPEG) - Data file (txt)


COM Port

Failing to communicate with the YSI 4600 thermometer.
1 -- Close the UNC Calibration Check software.
2 -- Download and open "RS232TST05RTS.exe".
3 -- Clicking the up and down arrows you can find out which serial ports are available on your computer. If  the back  color is red, the port is not available on your computer, if  yellow, the port is available.  When you select the port to which the thermometer is connected, the Thermometer LCD should display "H232"
4 -- Once you have found the right port, select the "RS 232 Data Out": "Any data to be sent, goes here" and replace it with the letter "T", then click "Send".
5 -- If the thermometer does not start sending the temperature (which will appear in the "RS 232 Data In" blue box) you must have a bad cable. Else send me an email at the address below.

Unavailable COM port Wrong but available port Right port

Parallel Port

Failing to receive the Pathway TTL Out signal.
1 -- Make sure that the signal line from the Pathway BNC is connected to pin 10 (Acknowledge) of the 25 pin parallel port connector, and that the BNC shield is connected to a grounded pin. Pins 18 to 25 are all supposed to be ground/common.
2 -- From the computer "Start" menu start the application at "All Programs\Accessories\Command Prompt".
3 -- At the DOS prompt type the following without the quotation marks: "debug" [Enter].
The PC will respond with: "-"
Type: "d 0:400".
The program will dump some of the PC memory starting  at the address 0:400 hex. At the middle of the first line, after the delimiter sign "-", will be the address of your LPT1 followed by LPT2 and LPT3 etc. The bytes are reversed, so "BC 03" means "03BC", "78 03" means "0378" etc.
4 -- Before closing the window you should type : "q" for Quit.

debug LPT

5 -- Alternatively you can find the LPT port address through the "Control Panel" For some reason the control panel seems to give me 0378 hex for LPT1 but the DEBUG program gives  03BC.
LPTtest.exe panel

If the program still fails to receive the TTL trigger from the Pathway, try the following
1 -- Close the UNC Calibration Check software.
2 -- Download and open "LPTtest.exe" (shown at right).
3 -- If the LPT Port Address is correct and you short pin 10 to ground  you should see the same display as displayed at right. Disconnecting the TTL Out BNC at the Pathway should cause the LTP Status bit 6 (pin 10) indicator to turn to a bright red color.

  To: Medoc TSA II & Pathway

2006 September 15