GEM Series Technical Support

Introduction to Data-Logging

Logging of engine temperature data on a routine basis allows the creation of a complete engine-operation history, a detailed record documenting each hour of an engine's life.

Data-logging with the GEM 610 and GEMINI 1200 provides the benefits of long-term trend monitoring through a standardized personal computer interface. The GEM data-log system makes it easy to retrieve log data from all flights.

The GEM 610 and GEMINI 1200 automatically record parameters during every flight. Each flight's data is stored in an individual log file in non-volatile memory. Every file has an identification header containing the date, time, aircraft- registration and data log configuration. All temperatures are sampled and recorded every six seconds during flight (ten records per minute), and are encrypted using the proprietary Insight-Compression-Algorithm (ICA). ICA compression of flight data allows up to 50 hours of flight log to be stored on 32 Kilobytes of computer disk space. Encryption of the log ensures the integrity and security of the recorded flight data. NOTE: Actual hourly capacity may vary widely depending on configuration, installation, operator technique, and many other variables. GEMINI 1200 systems typically store 10 to 20 hours of flight time, GEM 610 systems 20 to 30 hours.

Data acquired with the GEM 610 or GEMINI 1200 can be viewed directly in raw form, or imported into spreadsheet and database programs for graphical analysis.

The Infra-Red Communication Interface

Infrared (IR) data-communication technology is used to transfer information between the HP computer and the GEM 610 and GEMINI 1200. The IR communication link uses light instead of wires to convey information between devices. The HP computer has an IR communication port located on it's right side, adjacent to the wired communication port and the back-up battery. The GEM 610 and the GEMINI 1200 have IR ports built into their displays. To use the IR wireless interface, the HP's IR port must be within view of the GEM display.

Optimum position of the HP for communication with the GEM is 6 to 12 inches directly in front of the GEM display.

Some practice with the IR COMM TEST function of the GEMCOM software will demonstrate the best position and range. The GEM's display will exhibit a swimming- effect during IR communication. This effect is normal and is a positive indication of IR activity. Consult the HP User's or Quick Start Guide for additional IR port information.

GEMCOM - INSIGHT'S Software for the HP

The software program called "GEMCOM" was developed by Insight Instrument Corporation to provide remote control and data transfer functions between the GEM 610 and GEMINI 1200 displays and the HP.

GEMCOM Compatibility

GEMCOM was specifically designed for use with HP computers but will run on most computers that use DOS- or a compatible operating system. Note that wireless data-communications with a GEM 610 or GEMINI 1200 require a Hewlett Packard Infra-red communications port. GEMCOM can be run on a desktop or other personal computer to EXPAND compressed data files from the archive form to ASCII format.

How to create GEM Icon on HP 200LX - Palmtop

To create Icon GEM on HP 200LX - Palmtop go to Icon desktop push F2

Name: &GEM

Path: C:\GEM\GEMCOM.EXE |

Tab down to Icon.

Then push F10

F7 to arrange icon ( put in upper left with directional keys )

Then push enter.

Manual Start of GEMCOM:

GEMCOM can be manually started from within the FILER by highlighting the "GEMCOM.EXE"- file, and pressing ENTER. Selecting "Q"- from the GEMCOM Main Menu returns control to the FILER.

GEMCOM provides access to all functions through a standard screen menu system. Functions are selected by pushing the Number Key corresponding to the desired selection ( "1", "2", etc. NOT the -"F1", "-F2" function key). Menu functions that perform Infra-red communications are indicated by a double arrow symbol after their menu number, eg. "2>> GEM CLOCK-". Other functions provide a sub-menu of options, eg. "4) EGT BAR HEIGHT"-.

1) HELP!

On-line help provides a brief overview of each function. First press the F1 key for the help prompt, then press the number key for the subject you want information on. The help messages are contained in a file named "gemhelp"-. This file must be in the same directory as the main program ("GEMCOM.EXE"-) for the help feature to work.

2>> GEM CLOCK

GEM CLOCK is the GEM 610's and GEMINI 1200's on-board internal clock/calendar. Logged data is time/date stamped according to the GEM CLOCK time and date. The GEM CLOCK is factory set to UTC (a.k.a. ZULU or GMT) but can be set to any desired time.

The HP clock and calender is the master clock in the GEM system. To change the time or date on the HP use the built-in SETUP function:

1) Quit GEMCOM and press [SHIFT] [SETUP].

2) For time, press "t"- for time, then "c-" for current, and type the new time at the prompt and press [ENTER].

3) For date, press "d"- for date, then c- for current, and type the new date at the prompt and press [ENTER].

To access the GEMs internal clock, perform the following actions:

1) Run GEMCOM on the HP. Point the HP at the GEM 610 or the GEMINI 1200 display and select GEM CLOCK (press "2"). The HP will interrogate the GEM for its current date and time.

2) The HP will display the GEM CLOCK time and the HPtime, and offer to reset the GEMs internal clock to match the current HP time. Depressing "Y"- or "y-" causes the HP to synchronize the internal clock of the GEM to that of the HP. Depressing "N"- or "n"- aborts the process and returns to the Main Menu.

3) GEM CONFIG

Characteristics of the GEM 610 and the GEMINI 1200 Displays are controlled by the GEM CONFIGURATION. The GEM CONFIG function reads and updates the GEMs configuration status.

Configuration options include: Aircraft Registration, Number of cylinders per engine, Number of turbochargers per engine, OAT and IAT probes, and Fahrenheit or Celsius temperature scales for the digital display.

When enabled, the REMINDER will flash an "F" for Fahrenheit or a "C" for Celsius whenever the digital numeric selection is changed.

To check or change the configuration of a 610 or 1200 perform the following actions:

1) From GEMCOM's main menu, point the HP and select GEM CONFIG (press "3") to read the current display configuration. The HP will get the current configuration data from the GEM and display it on the GEM CONFIG MENU.

2) If required, modify the configuration shown on the HP to match the actual installation:

3) Point the HP again and select the UPDATE CONFIG (press 9") option to reprogram the GEM display. If no change to the configuration is required, press "q" to return to the MAIN MENU.

4) Repeat action No. 1 if desired to confirm the new display configuration.

1) Enter aircraft's registration number.

2) Enter 4 or 6 for number of cylinders.

3) Enter number of turbos.

4) Enter "O" for OAT only, "I-" for IAT only, "BOTH" or "NONE".

6) Not implemented.

7) Select "F" for Fahrenheit or "C" for Celsius scales.

4) EGT BAR HEIGHT

Indicated EGT values vary between engines defendant on specific location of the EGT probes. The GEM bar-graph display works best when the highest EGT column is even with the Reference Asterisk- at normal power and mixture settings in cruise flight. (See Figure 6 & 7) The EGT BAR HEIGHT function allows adjustment of the GEMs EGT bar-graph height. Adjustment of the EGT BAR HEIGHT may be performed in-flight or post-flight, based on observations.

To adjust bar height perform the following actions:

1) From the main menu, press "4", the EGT BAR HEIGHT function sub-menu will appear.

2) Point the HP at the GEM and select READ BAR HEIGHT (Press "3"). The HP's message line will report the current EGT BAR HEIGHT setting(s) as a number of bars up or down (from nominal).

3) Change the bar-graph height settings on the HP's message line by selecting EGT UP or EGT DN as required.

4) Point the HP at the GEM and select UPDATE BAR HEIGHT.

5) Repeat steps 1 to 4 to re-adjust or confirm new setting.

6) DATA TRANSFER

Software version 1.1X features advanced data-logging, data-transfer and file management capabilities. During flight, the GEM samples all temperatures specified in the data-log configuration and records temperature changes at six second intervals (ten records per minute). Data-logging automatically begins at instrument power-up and continues until shut-down. Data-log files can be transferred from the GEM to the HP at any time.

NOTE: Intensive IR communications require near-full main batteries (AA size), or the use of an external power adapter to avoid draining the HP's batteries during use.

The DATA TRANSFER functions allow the user to get a list of log files contained within the GEM, and then transfer a single file or group of files.

LIST FUNCTIONS:

1>> LIST ALL FLTS - lists all log files contained in the GEMs data-log memory.

2>> LIST ONLY FLTS - lists only those flights that have not yet been transferred from the GEM to the HP.

3>> LIST LAST FLT - lists the current log file in the GEM.

4) EXPAND FILE - not really a TRANSFER function, but a shortcut to the EXPAND FILE menu. Data files transferred from the GEM to the HP are encrypted in IDF or ADF format. The EXPAND FILE functions will convert the encrypted files to ASCII format for immediate viewing or further processing. See the DATA FILES section for more information on file formats.

NOTE: A minus sign preceding a file name in a listing of data files indicates that the file has already been transferred to the HP. The transfer function does NOT erase the original data-file from the GEM's memory and the file may be transferred again.

TRANSFER FUNCTIONS:

The transfer functions will copy data files from the GEM to the HP. If a group transfer (TRANSFER ALL or TRANSFER ONLY) is performed, an ADF file will appear in the HP in the current subdirectory. If a single flight is transferred (TRANSFER ONE or TRANSFER LAST), an IDF file will appear. The default subdirectory for GEMCOM is "C:\GEM".

Data is transferred across the IR link at rate of 125 bytes per second. A data file (IDF or ADF) of 1000 bytes will take eight seconds to transfer from the GEM to the HP.

Note that IDF and ADF files need to be EXPANDED to ASCII format before the data can be viewed.

5>> TRANSFER ALL - transfers all the log files contained in the GEM's log memory. If the GEMs memory is full, this transfer could take up to four minutes to complete.

6>> TRANSFER ONLY - transfers only those log files that have never yet been transferred.

7>> TRANSFER RECENT - transfers the most recent flight file.

8>> TRANSFER ONE - transfers a single file chosen from a group list. The time required to transfer a single log file is dependant on the length of the flight data file. A short file will only take a few seconds to transfer. Specify the file by it's flight number shown by the LIST function.

To transfer data-log files from the GEM to the HP, perform the following actions:

1) Point the HP at the GEM and get a list of the available file(s) using the appropriate LIST function.

2) Point the HP again and transfer the selected file(s) using the appropriate TRANSFER function.

NOTE: Transferring a file from the GEM to the HP does not erase the original file from the GEM's non-volatile memory.

A copy of the data-file is created in the HP. The original data-file in the GEM's memory will exist until over-written by new data.

7) DATA LOG CONFIG

The DATA-LOG CONFIG controls which temperatures are recorded during the data-log process. The DATA-LOG CONFIG will by default mirror the GEM CONFIGURATION but can be modified by turning-off unwanted channels.

To check or modify the DATA LOG CONFIGURATION perform the following actions:

1) From the GEMCOM MAIN MENU, select DATA LOG CONFIG (press "7") and then point the HP at the GEM and press [ENTER] to read the current logging configuration.

2) The current logging configuration will be displayed on the HP. Use the cursor keys to move the blinking underline cursor to the item to be modified, and press [DEL] to toggle the item's status on or off. When turned-off, an item will be shown as an "X" on the menu.

3) Point the HP at the GEM and select UPDATE (press "1") to transfer the new logging configuration into the GEM, or press "q" to return to the main menu without changing the GEM.

When to use DATA LOG CONFIG

The main purpose of Logging-Configuration is to allow the selective exclusion of data from the logging process.

Some users may wish to maximize data log hour capacity by excluding unwanted data from the logging process. For example, excluding all EGT data and logging only CHT and TIT would increase log capacity by a factor of several times (CHTs tend to be more stable than EGTs due to the cylinder head's relatively large mass and long thermal time-constant.)

Electrical noise from malfunctioning engine accessories (ex. ignition system or battery charging system), may affect the GEM's temperature measurments. Typical symptoms of electrical interference include jittering temperature indications on the GEM's display. To prevent a noisy temperature channel from consuming data-log capacity, temporarily exclude the affected item(s) from the LOG CONFIG until repairs can be performed.

GEM's sensitivity to electrical noise may alert you to impending electrical or ignition system problems before they become obvious or even detectable by other instrumentation. Do not ignore unusual or erratic indications!

8) EXPAND FILE MENU

Each minute of flight time will require appoximately 1000 bytes of file storage space for the expanded ASCII file. Allow about 60 kilo-bytes of storage space for each flight-hour.

See the DATA LOGGING and DATA FILES section for more information on file formats.

Expand Functions:

1) EXPAND FILE - expands the highlighted file and creates a new file(s) in ASCII format. The new file(s) will have the same name as the original but with an ASC- instead of IDF- or ADF-. Use the cursor keys to move the highlight bar up and down the file list. If more files exist than will fit in the viewing window, the list will scroll as required.

2) CHANGE DIRECTORY - allows you to select a different subdirectory as the source of files for expansion. Useful for managing files from more than one aircraft.

Q) Return to MAIN MENU.

9> IR COMM TEST

The IR COMM TEST allows testing of the HP and the GEM 610 and the GEMINI 1200 wireless infrared communications interface. To test the IR link perform these actions:

1) Select IR COMM TEST (press "9") and point the HP at the GEM. The optimum position of the HP is six to twelve inches squarely in front of the GEM. The GEMCOM status message will indicate when the IR link is connecting. Audible "beeping" of the HP indicates successful IR communications.

2) Press ESC to terminate the IR COMM TEST and return to the main menu.

Note that sustained use of the IR link, such as when running the IR COMM TEST function draws heavily on the HP's internal batteries. Don't forget to press [ESC] to terminate IR testing when done.

Q) QUIT

QUIT exits GEMCOM and returns control of the HP to the operating system.

Data-Logging

The GEM's Data-Log System

The GEM automatically opens a new data-log file each time power is applied to the display. A data-log file consists of an identification (ID) header followed by the encrypted temperature data. The ID header contains the Aircraft Registration, log file serial number, starting date and time, flight duration, temperature scale, and data-log configuration.

Logging is controlled by the DATA LOG CONFIGURATION. The log configuration defaults to mirror the display configuration but can be modified using the DATA LOG CONFIG function of GEMCOM.

Switching the GEM off and then restarting it during flight will cause it to close the current data file and open a new one. Changing the GEM CONFIG or the DATA LOG CONFIG will reboot- the GEM, causing the old data-log file to be closed, and a new one to open.

The data compression system is most effective on long cross-country flights with stabilized temperatures. Short flights with frequent temperature changes will fill the GEM's data-log memory more quickly.

It is important to transfer log data to the computer periodically. When data-log memory is full, new data files will overwrite and destroy the oldest data, files that have not been transferred are permanently lost. At any given time the GEM will contain the log files from the most recent flight(s).

Data Files

The GEM data-log system uses three different types of files to manage logged data: Individual Data Files (IDF) , Archive Data Files (ADF), and ASCII data files (ASC). The IDF and ADF files are much smaller in size than corresponding ASCII files. Smaller files can be transferred in less time and require less disk space for storage.

1) Individual Data File (IDF) - contains an identification header (ID header) and the encrypted data from a single flight. Each IDF file is named after the flights log serial number. Example: "FLT7.IDF". IDF is the native file format for the GEM logging system.

2) Archive Data File (ADF) - contains two or more IDF files, and a FLIGHT INDEX listing the contained IDF files. Each ADF file is named after the lowest flight-serial-number that it contains. Example: "FLT001.ADF" could contain the IDF files from flights 1, 2, and 3.

3) ASCII data file (ASC) - contains the ID header and data from an IDF file, but with the data expanded to ASCII format. ASCII is the American Standard Code for Information Interchange. The ASCII data format has the advantages of being readable and widely compatible with most types of computers, but at the expense of file size.

For example: "FLT123.ASC" would contain the same information as "FLT123.IDF", but theASCII version of the file could be as much as 100 times larger in size.

The small size of the IDF and ADF files make them ideal for transfer and storage of data, ASCII files can be viewed directly on the HP's FILER, or IMPORTED into a spreadsheet program.

See the USING THE HP and DATA TRANSFER sections for details on transferring files from the GEM to the HP.

Viewing Data Files

The ASCII data files created by GEMCOM's EXPAND FILE function can be viewed directly on the HP, but can benefit greatly from the larger screen and more powerful features usually provided by a desktop or comparable personal computer.

Viewing Data Files on the HP:

Use the built-in FILER program on the HP to view the contents of any log-files ID header.

To view a file on the HP95LX; run the FILER, use the cursor keys to highlight the filename to be viewed and press [ENTER].

To view a file on the HP200LX; run the FILER, use the cursor keys to highlight the filename to be viewed and press [F8].

D HEADER of an IDF file viewed by the FILER:

Note that the data area of an IDF format file will appear as random ASCII characters due to the data-compression.

The EXPANDED (ASCII format) version of a data file can be viewed directly with FILER, the HP's cursor keys allow the view to be scrolled through the file.

ID HEADER of an ASC file viewed by the FILER:

Viewing Data Using a Spreadsheet:

An EXPANDED (ASC) version data file can be copied into a 123 spreadsheet on the HP. To run the spreadsheet program, quit GEMCOM and press the [123] button. To copy the data file into the spreadsheet, perform the following sequence of key presses: [MENU], "f", "i", "n".

Type the full name of the data file including the directory, ex. "GEM\flt123.asc", [ENTER].

Please consult the HP User's Guide for details on using the FILER, 123, and any other HP built-in application.

Viewing Data on a Desktop PC

Desktop or comparable computer offers many advantages for viewing and working with data-log files. The ACSII format (EXPANDED version) GEM data file is compatible with most computers and application programs.

Copying files from the HP to other computers use flashcards.

Spreadsheet programs are readily available for virtually every make and type of computer. Most spreadsheet programs provide the features needed to manipulate data files, including graphical functions.

A File Management Strategy

Consult the NOTES section for information on sources of computer accessories including data-communications and spreadsheet products.

Periodically, (depending on how often the airplane flys) transfer all the new data files from the GEM to the HP using the TRANSFER ONLY function. This will generate an ADF format file in the HP containing only the flights that have never before been transferred.

Using a serial interconnection cable and data-communication software, copy the ADF files from the HP to a desktop or full-screen portable computer.

Back-up the ADF files for safe-keeping.

Expand the ADF files to ASCII format for routine viewing and analysis. Delete the ASCII versions after viewing. They can be recreated from the archive IDF or ADF files if required for future review.

Keep the ADF files for efficient long-term storage of the data.

To reduce the risk of losing any data-files in the GEM before they are over-written by new data, transfer data from the GEM to the HP after every flight.