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EIS serial output
Posted: Thu Apr 24, 2014 3:27 pm
by rjb
I'm trying to do some evaluation for a CHT temp issue right now, and would like to put the data into a spread sheet, VB, or something similar. I can get the data into EIS log but want to do something more. Could anyone explain the data format,and if there is anything I can do with it?
I'm not understanding how the serial data is coming out?
Thanks for any help, suggestions
Ron
RV9A
Re: EIS serial output
Posted: Thu May 01, 2014 12:56 am
by GRT_Jeff
The EIS Log data can be saved to a spreadsheet format. When you use File, Save As in the EIS Log program, use the file name extension ".csv". The data will be in the same order as in the program.
The EIS unit sends out data in a binary message, not a simple text format. If you would like to try reading the data directly, we will e-mail the serial interface document upon request.
Re: EIS serial output
Posted: Tue Apr 14, 2015 3:36 pm
by Gil
Hello Sir,
We are using Model 4000/6000 EIS and would like to connect to it's serial interface for data reading.
1. Is it standard RS232 or UART (TTL ) interface?
2. Could you send me the Communications protocol.
Thanks for your assist,
Gil.
Re: EIS serial output
Posted: Wed Apr 15, 2015 1:11 pm
by JimB
Gil,
Go to the EIS Programming thread. There is a post by me of EIS Data which Jeff answered with the information you need.
Jim Butcher
Re: EIS serial output
Posted: Mon Jan 26, 2026 1:30 am
by bzollars
GRT_Jeff wrote: Thu May 01, 2014 12:56 am
The EIS Log data can be saved to a spreadsheet format. When you use File, Save As in the EIS Log program, use the file name extension ".csv". The data will be in the same order as in the program.
The EIS unit sends out data in a binary message, not a simple text format. If you would like to try reading the data directly, we will e-mail the serial interface document upon request.
Hi Jeff,
Could I please obtain a copy of the EIS serial output protocol document? I am developing a graphical display of some quantities computed from items in that data stream.
Thanks in advance,
Byron
Velocity N108BG
Re: EIS serial output
Posted: Tue Jan 27, 2026 7:08 am
by GRT_Jeff
It doesn't attach correctly here but I can put it in a code block. It's just a plain text file.
EIS 4000/6000/9000 serial data format
Code: Select all
Model 4000/6000 Serial Data List
All data is transmitted at 9600 baud, one stop bit, no parity. The first 3 bytes are a header
that is unique, and will not show up in the data stream.
All 2 byte data is listed with an "H" and an "L" following the name of the data. To combine these
two bytes into the result, multiply the high word by 256 and add the low word to the result.
All data is scaled with the least significant bit = 1 unless noted. All data is unsigned unless noted.
$FE ; Header word #1 (Decimal 254)
$FF ; Header word #2 (Decimal 255)
$FE ; Header word #3 (Decimal 254)
TACHH ; Tachometer - Resolution = 1
TACHL
CHT1H ; CHT and EGT follow all have
CHT1L ; a resolution of 1 deg
CHT2H
CHT2L
CHT3H
CHT3L
CHT4H
CHT4L
CHT5H
CHT5L
CHT6H
CHT6L
EGT1H
EGT1L
EGT2H
EGT2L
EGT3H
EGT3L
EGT4H
EGT4L
EGT5H
EGT5L
EGT6H
EGT6L
AUX5H ; Auxiliary 5 (TIT 1 for instruments with TIT option including Chelton version)
AUX5L ;
AUX6H ; Auxiliary 6 (TIT 2 for instruments with TIT option including Chelton version)
AUX6L ;
ASPDH ; Airspeed (units are the same as displayed on the EIS)
ASPDL ;
ALTH ; Altitude in tens of feet, 2's compliment
ALTL
VOLTH ; resolution of 0.1 Volts
VOLTL
FUELFH ; Fuel Flow (Gallons/Hour) resolution of 0.1 gallons/hour
FUELFL ;
UNIT ; Internal Instrument temperature
CARB ; 2's compliment
ROCSGN ; Vertical speed - 100 fpm resolution 2's compliment
OATH ; Unsigned 8-bit value offset by +50, except on Chelton
OILTH ; Oil Temperature
OILTL
OILP
AUX1H ; Auxiliary 1
AUX1L
AUX2H ; Auxiliary 2
AUX2L
AUX3H ; Auxiliary 3
AUX3L
AUX4H ; Auxiliary 4
AUX4L
COOLH ; Coolant Temperature (or TACH3H if this is enabled on in the EIS software)
COOLL ; (or TACH3L if this is enabled on in the EIS software)
ETIH ; Hourmeter - Resolution = 0.1 hours
ETIL ;
QTYH ; Fuel Quantity (fuel flow totalizer) Resolution = 0.1 gallons
QTYL
HRS ; Flight timer hours
MIN ; Flight timer minutes
SEC ; Flight timer seconds
ENDHRS ; Fuel FLow time until empty - Hours
ENDMIN ; Fuel FLow time until empty - Minutes
BAROH ; Baroset in In HG - Resolution 0.01
BAROL ;
TACH2H ; Tachometer2 - Resolution = 1
TACH2L
SPARE ; Reserved.
Checksum (data summed and result complimented) is transmit here - 1 word. The checksum
does not include the header, but does include the "SPARE" word. The checksum is a single,
8-bit word.
Re: EIS serial output
Posted: Tue Jan 27, 2026 6:41 pm
by bzollars
Thank you, sir!
Re: EIS serial output
Posted: Sat Jan 31, 2026 11:02 pm
by bzollars
Hi Jeff,
A few additional questions about the data in the serial output stream:
1. I notice that the EIS has a "Serial In" line on Connector A. This is not hooked up in my aircraft, but I wonder if it is used for anything?
2. The data fields (ASPDH,ASPDL), (ALTH,ALTL), and ROCSGN imply that the EIS can be attached to the pitot-static system. My aircraft gets these data into the EFISs from AHRSs, so I am wondering what these fields read? There are no additional pressure inputs to the EIS apparent.
3. Are the data for the Aux1-Aux6 channels raw ADC values, or do they have the EIS transfer function applied prior to insertion into the serial stream? If raw, what is the corresponding ADC value for 5V input, 0xFFFF?, 0x0FFF?
4. I assume that the (QTYH,QTYL) field is the fuel flow since EIS boot. Since the EIS does not know if/how/where fuel gauges are connected, how are the ENDHRS and ENDMIN (time until empty) fields computed?
5. Which of these values in the EIS serial output are ignored by the EFIS?
Thanks!!
Byron Zollars
Velocity N108BG
Re: EIS serial output
Posted: Tue Feb 03, 2026 8:05 am
by GRT_Jeff
bzollars wrote: Sat Jan 31, 2026 11:02 pm
1. I notice that the EIS has a "Serial In" line on Connector A. This is not hooked up in my aircraft, but I wonder if it is used for anything?
On an EIS with its own display and buttons, the Serial In is only rarely used for updating software (on units with that hardware capability), so it is not normally wired. On the remote model R66, it is used for some configuration so it is always wired.
bzollars wrote: Sat Jan 31, 2026 11:02 pm
2. The data fields (ASPDH,ASPDL), (ALTH,ALTL), and ROCSGN imply that the EIS can be attached to the pitot-static system. My aircraft gets these data into the EFISs from AHRSs, so I am wondering what these fields read? There are no additional pressure inputs to the EIS apparent.
The EIS has to be ordered and built with airspeed and altimeter options for those fields to work. Normally with an EFIS you wouldn't have those. Due to some limitations with using them for the EFIS, the EFIS simply ignores them.
bzollars wrote: Sat Jan 31, 2026 11:02 pm
3. Are the data for the Aux1-Aux6 channels raw ADC values, or do they have the EIS transfer function applied prior to insertion into the serial stream? If raw, what is the corresponding ADC value for 5V input, 0xFFFF?, 0x0FFF?
For an EIS with its own display and buttons, the Aux fields contain the converted values using the scale factors and offsets programmed into the EIS.
bzollars wrote: Sat Jan 31, 2026 11:02 pm
4. I assume that the (QTYH,QTYL) field is the fuel flow since EIS boot. Since the EIS does not know if/how/where fuel gauges are connected, how are the ENDHRS and ENDMIN (time until empty) fields computed?
The fuel totalizer function subtracts fuel flow from the initial fuel total that you enter. The QTY field is the fuel remaining after subtracting fuel flow. This only works if you are entering the fuel total into the EIS, and you have fuel flow. It stops at zero. A value in this field overrides the fuel total setting in the EFIS as the EFIS assumes you are entering the fuel total using the EIS and the EIS will be keeping track of it.
bzollars wrote: Sat Jan 31, 2026 11:02 pm
5. Which of these values in the EIS serial output are ignored by the EFIS?
Airspeed, altimeter, vertical speed, baroset, and fuel flow time until empty are stored but always ignored by the EFIS. Some fields may be ignored depending on configuration and user entries, such as zero fuel remaining, extra EGTs/CHTs. The EFIS calculates its own fuel endurance.