The LI-6800 is equipped with ample self-testing combined with status messages and warnings shown in the upper left corner of the display, which alert you to issues in the system. Pay attention to these. An ignored error message can lead to poor experimental outcomes and poor-quality data. Errors are color-coded to indicate severity. A Red message indicates a problem and Yellow indicates potential concern. The potential errors are given in Table 5‑2.

Status messages

Table 5‑2. Status messages given on the display.
Message What it means
**Log Pending** Displayed during a log event, which can be very short, or a few seconds if it has to wait for a fluorescence event, or several seconds if matching has to happen.
<program name> paused When a program is active, but paused.
<program name> running When a program is active.
Auto CO2 The various automatic environmental controls that can be active. These messages indicate which auto control is active. When more than one control is active the messages will cycle across the display.
Auto Fan
Auto Flow
Auto H2O
Auto Light
Auto Temp
Auto Match When the instrument is running the automatic match algorithm.
Manual Match When the instrument is in the manual match mode, waiting for you to do the match and exit. (To exit this mode, press the OK button.)
SysTest: <name> Warmup or system test is running.
AutoDry AutoDry is an automatic drying routine that kicks in if the humidity gets > 99% in the chamber or one of the IRGAs.
PostFlash PostFlash is a “post fluorescence flash stabilization routine”. If you do a fluorescence flash while doing leaf temperature control, and/or leaf VPD water control, right before the flash these controls are “locked" so they don’t react to the pulse in leaf temperature that will result from the flash. It lasts for 30 seconds.

Warning messages

The following are warning messages that might appear on the display.

Table 5‑3. Warning messages given on the display.
Message What it means
<List of one or more temperatures> When a temperature sensor is reading >80 °C or <20 °C, it appears in this warning list. The temperature sensors that are checked (besides Tleaf and Tleaf2) are Ts (sample cell), Tr (ref cell), Tirga (IRGA block), and Tair (chamber air temp).
Chopper Not Locked Unable to record position of the optical chopper. Triggered by head status bit 0x2000. To resolve it, try putting the instrument into sleep mode and take it out of sleep mode. If that doesn't work, restart the instrument. If that doesn't work, call technical support.
Close Cmbr for <xxx> ctrl When doing CO2_s or H2O_s control, the chamber needs to be closed. If it is not, this message appears. Close the chamber to resolve it.
CO2 Cartridge Low/Empty These messages are triggered from the value of CO2_FLOW_STATUS value being <0.05. If it is in this condition with a low CO2 setpoint, the cartridge is likely empty. Otherwise, it is getting empty, and higher CO2 targets are no longer possible.
CO2 too high to control
Console flow leak? These messages indicate a potential issue with the flow path in the console, either a leak (chemical tube missing, or end cap loose), or a constriction. The specific thing that triggers these messages is the PUMP_PRESSURE_STATUS value: > 4.9V indicates a constriction, and < 0.1V indicates a possible leak.
Constricted flow?
Cooler target less than Td The target you picked for the cooler is lower than the dew point temperature. To resolve it, pick a warmer target.
Cooler Td limited The cooler cannot lower the temperature as fast as it normally would, because that would require driving it to a temperate below the dew point temperature. This message doesn't necessarily mean condensation is a problem; it just means the cooler is not being driven as hard it could be in drier air.
Fan Fail Cooling fan or chassis fan is not functioning as expected. Triggered by head status bit 0x0400. Cycle power. If it recurs contact technical support.
Flow_r low Flow control is ON and Fr or Fs is <25 µmol s-1. The usual reason for the Flow_s Low message is the chamber being open. One or the other of these may appear during Warmup tests.
Flow_s low
Flr DC Overrange The fluorometer has over-ranged its modulated signal. This doesn't hurt anything, it just suppresses the modulated fluorescence signal. It is also hard to do: it pretty much needs a direct glimpse of full sun reflected up into the detector to over-range it.
Flr DC Saturated The fluorometer DC signal is saturated. Diagnostic bit 0x800.
Flr Measuring Off The fluorometer measuring beam is off (Qmod_avg is 0.0). (The fluorometer is still modulating, but with 0 intensity. This is typically the state when you turn measuring off.)
Flr Mod Off The fluorometer’s modulation is turned off. Diagnostic bit 0x2000. This should be a very temporary condition, because whenever it is detected and the fluorometer is connected to a console, the scripts attempt to turn it back on.
Flr Q Saturated The fluorometer photodiode is saturated. Diagnostic bit 0x400.
Flr Temp Warning The fluorometer has a temperature issue. Turn it down or off and let it cool for a few minutes. Diagnostic bit 0x1000.
Head Powered Off The head has been put in a low power state (Power Saver (2)), but it was not done from the console.
High RH: xx% <sensor> A high humidity warning appears when the RH is higher than 90% in the chamber or either of the IRGA cells. The value of the humidity is shown, and also the location (in terms of the temperature sensor). Ts (or Ta) is sample cell, Tr (or Tb) is reference cell, and the rest (Tleaf, Tair, Txchg) are the leaf chamber. If RH exceeds 99%, the AutoDry program is launched to bring down the humidity and prevent condensation.
LI-6850 Factory Cal Indicates that one or more factory calibration values has been altered or that the information cannot be found. Go to Start Up > Calibration and pick Factory Coefficients from the menu.
Low Battery Install a charged battery or plug in the console power supply
Match Valve Open A normal measurement has the match valve closed, so sample air goes to the sample IRGA and reference air to the reference IRGA. This message will be displayed anytime the valve is not in that state, which, in normal operation, will be during matching and during some system tests. To resolve it, go to match screen, select manual match, then tap OK to leave manual match.
No Console This message indicates the sensor head has no "back channel" connection with the console, which means the head will not be able to control the pump, or chemical tube valves, etc. on the console. Flow control, CO2 control, H2O control will be adversely affected. This message comes from a diagnostic bit 0x02 from the head. Cycle the power to resolve it.
Power Saver (1) Power Saver (1) appears while the system is in the Conserve Chemicals mode, with all environmental controls turned off.
Power Saver (2) Power Saver (2) means it is in the Conserve Power and Chemicals mode, which has Chemical Saver on and the sensor head in a low power state.
TEC Fail The Thermo Electric Cooler has failed, or more likely tripped its overload protection. The message is triggered by status bit 0x0800. Cycle the power to resolve it.
TLeaf Both Tleaf and Tleaf2 are missing or reading >80 °C or <-20 °C.
x Ver Flr (need y) Software versions not matched. It means the head or fluorometer has a software version that is out of sync with the console version. Example. "1.0 Ver Head (need 2.0)"
x Ver Head (need y)
QMQTT Remote Host Closed Potential issue in software version 1.5 and older; the interface is unable to communicate with the instrument. Update the instrument to resolve the problem. If you want to continue running older software, consider the following: If you are running a Program, it will probably continue running, so, if you are in the middle of an experiment, wait for the measurement to finish running. You may be able to reconnect under Tools > Connections, by tapping Disconnect and then Connect. If you are unable to reconnect, quickly press and release the power button to restart the interface.