Troubleshooting

Here we describe how to identify and resolve problems that may arise, starting with connection issues and finishing with diagnostic information.

LI-720 troubleshooting

Connection issues

Most connection issues can be resolved by checking the wiring connections or the data logger configuration.

• If connecting to a PC with the CarbonWare app, is it using the correct serial port?
• Typically, only valid serial ports are listed. You can try them one at a time or check the port number assignment in you computer Device Manager. To find the serial port number, open the Device Manager (press the Windows key , type Device Manager, then press Enter). Click Ports (COM & LPT). Look for USB Serial Port (COM#). The serial port numbers are shown beside the ports.
• Power supply inadequate?
• If connecting to a PC with the USB cable, do not extend the cable. Voltage drops over a long cable can cause problems with the power supply (not enough power) or digital communication.

Measurement issues

• Air temperature and RH readings implausible or -9999?
• The sensor unit may have failed. See Replacing the air temperature and RH sensor.

Flux diagnostics

Before computing any results, the LI-720 filters implausible values from the 10 Hz raw data. A diagnostic code is provided for every computed result. The diagnostic code can reveal more about what was wrong with a particular measurement, details about environmental conditions for the time period, and information about the LI-720 performance over that time period. Some diagnostic codes are simply for your information - there is nothing to do besides know what the code indicates. Other codes may indicate that service is required. A few are reserved. A diagnostic code of 0 indicates normal operation.

Decoding the diagnostic

The diagnostic code is a 16-bit binary value encoded as a decimal value. It is included as the last parameter in output groups 0 and 1. The decimal value ranges from 0 to 65535 (corresponding to bit positions 0 through 15). It encodes up to 16 issues.

You can decode the diagnostic from decimal to binary using the calculator included with your computer operating system (Windows and macOS; select programmer mode). Enter the diagnostic value and observe the positions of the 0s and 1s in the binary results. Associate the 1s with the descriptions in Table 8‑1.

Table 8‑1. A diagnostic code is included with each flux result. A diagnostic is triggered if the threshold was exceeded for more than 10% of samples in a measurement period.

Bit Position	DEC	Description	Threshold
-	0	Normal operation	No issues reported
0	1	Sonic temperature - vertical	t_sonic <-25 or >50 °C
1	2	Sonic signal quality - horizontal
2	4	Sonic signal quality - vertical
3	8	Temp/RH sensor	1 = error; 0 = OK
4	16	Temperature	ta <-25 or >50 °C
5	32	RH sensor	RH >100 or <0%
6	64
7	128	Lamp temperature	t_src <-25 or >50 °C
8	256	Source RH scrub quality	RH_src >4%
9	512	Ambient pressure	1 = error; 0 = OK
10	1024	Ambient pressure	P<45 or > 115
11	2048	Signal strength (RSSI)	<80%
12	4096	Level sensor	1 = error; 0 = OK
13	8192	Compass	1 = error; 0 = OK
14	16384	Detector temperature	detector temperature <-25 or >50 °C
15	32768	PAR sensor reading	PPFD <-20 or >3000
16	65536	H2O out of range	H2O <10 or >60
17	131072	CO2 out of range	CO2 <-10 or >1500
18	262144	Missing sonic data frames	-
19	524288	Data storage invalid	Invalid JSON detected on startup
20	1048576	GPS and RTC	0 = GPS good; 1 = no update during interval
21	2097152	Flux QC flag	>40% of high speed data flagged as bad

IoE Module troubleshooting

If you encounter unexpected performance or other problems with the IoE Module, start here to find a solution.

Configuration problems

Configuration issues are related to communication between the IoE Module and attached sensors.

• SDI-12 devices not registered on the IoE module?
• Go through the steps in to configure the sensors.
• Unsupported device?
• Currently, the IoE module supports the LI-710, LI-720, and Stevens HydraProbe.
• Device cable disconnected?
• If a sensor has been configured but the cable is disconnected as you go through the configuration steps, the IoE Module will issue an error. Be sure the cables for all sensors are connected and select YES to try again.

Cellular or network problems

• Adequate cellular signal strength?

• Be sure there is a strong cellular signal. If you are near the IoE Module, check the signal status on the IoE module. From the home screen, press right () and down () to view the status. You should see signal strength and the name of the cellular provider. A strong signal is close to 0 dBm, while a weak signal is close to -120 dBm. Press Select to send a test data message to LI-COR . If you see any message besides PASS, or if the signal strength is outside the expected range, contact LI-COR.

Problems powering on

Power supply problems can be resolved by checking the cable connections and voltage of the source. A multimeter may be useful for measuring voltages.

• Power cables connected properly?
• See Attaching the solar power supply or Using an external power supply.
• External power supply problems?
• If using an external power supply, be sure it provides 10 to 33 VDC with 3.0 amp capacity.
• Battery depleted?
• Measure the battery voltage with a multimeter. If it is less than 11 volts, the device will power off until the battery voltage is above 12. Allow the battery to charge from the solar panel or charge it with a compatible external charger. If the solar panel is not delivering enough power to charge the battery, clean it and adjust the angle and orientation so it faces the sun.

Classes and conditions

The device interface presents classes and conditions that indicate a problem. Classes are a category and conditions indicate the type of problem (see Table 8‑2). Press left () once view Conditions.

With the exception of conditions that are triggered during the startup cycle, conditions will remain visible on the display until cleared, even if the issue is resolved. This is intentional so that operators can observe conditions that have been triggered previously. Press Select to clear past conditions and show only current conditions.

Table 8‑2. Classes, conditions, and the meaning.

Class	Condition	Meaning
Battery	Battery not connected	No voltage measured from a battery. Check battery connections.
Battery	Voltage low	Critically low battery voltage. Apply external power or use solar charger.
Battery	Voltage high	Charger malfunction.
Battery	Load current high	System board malfunction; drawing too much power.
Battery	Charge current high	Charger malfunction; possible short circuit in battery system.
Battery	Rntc out of range	Internal temperature sensor malfunctioning.
Cloud	Can't connect to MQTT broker	Cellular data is fine but connection to cloud back-end was refused. Most likely a security problem.
Cloud	Last cloud session failed	There was a problem during the previous cloud session. This should resolve at the next cloud session. If this persists, there's something else wrong.
Config	Bad or missing SDI-12 network info	SDI-12 Network is not configured. Run the configuration tool.
Config	Bad or missing modem info	CRITICAL PROVISIONING FAILURE – important configuration data for cellular connectivity is missing1 This can be cured by supplying this information to the IoE as a special file on an SD card.,2 Modem config (how to reach the cellular network), cloud config (credentials), serial number, and the security certificate are all backed up internally so they may be recovered automatically in case of memory corruption. If any of these are reported missing after a restart, this is a critical failure. All but the serial number can be re-imported to the device via the SD card if necessary. Contact LI-COR if you observe issues like this..
Config	Bad or missing cloud info	CRITICAL PROVISIONING FAILURE – device credentials for accessing the cloud service are missing1,2.
Config	No security certs	CRITICAL PROVISIONING FAILURE – device has no security certificates1,2.
Config	Bad or missing sensor info	Sensor configuration information missing (this is downloaded from LI-COR Cloud). This code should resolve itself at the next successful cloud session. Measurements cannot be obtained from a sensor with this problem.
Config	<sensor name> not supported	The named sensor is not supported by IoE.
Config	Bad or missing schedule	There is no schedule for measurements (run the configuration tool) or a schedule refers to a sensor for which configuration data is not available (should resolve at next successful cloud session).
GPS	Not locked	GPS location is unknown (also cannot synchronize to GPS time).
Logger	Card not mounted	SD card is either not present or was not mounted using the mount button3 The IoE module will work fine without an SD card, as long as there is a cellular connection. The SD card offers the following features, which are not available if the card is not mounted: CSV data files, backlog for data in case of cellular connectivity problem, backup of data in case of power loss before upload..
Logger	SD card FULL	SD card is <5% free4 The 8 GB card has space for years of data. The IoE will gracefully stop using a full card, but it's best to not get there that way..
Logger	SD card nearly full	SD card is <25% free.
Logger	Sensor data cache nearly full	The IoE is nearly out of room to hold data in RAM.
Logger	Sensor data cache FULL	The IoE is out of room to hold data in RAM. If an SD card is mounted and not full, data is also backlogged there, so nothing will be lost in this case.
Modem	Can't connect to network	Modem cannot connect to cellular network. SIM card issue, perhaps. Maybe no coverage or signal strength issue.
Modem	Low or no signal	Cellular signal is critically low or no connection at all.
Modem	Modem unresponsive or missing	CRITICAL HARDWARE PROBLEM – cellular modem is malfunctioning.
SDI-12	<sensor name> Read failure	Malfunction while reading this sensor.
SDI-12	<sensor name> Sensor doc bad or missing	Sensor configuration data went missing. This is unexpected but should self-correct at the next successful cloud session.
SDI-12	Bus voltage low	SDI-12 power supply malfunction or excessive load attached.
SDI-12	Bus voltage high	SDI-12 power supply malfunction or possibly there is an external power source applied (don't do that).
SDI-12	Bus current high	Excessive draw from attached SDI-12 sensors or wiring fault.
System	DEVICE MISSING SERIAL	CRITICAL PROVISIONING FAILURE – device has no serial number. This is indicative of acute system failure. Contact LI-COR.
System	No cloud connection since restart	This is a transient notice that simply lets you know the system has restarted and not yet successfully talked to the cloud service.
System	Scheduler halted	CRITICAL SYSTEM FAILURE – no measurements will be taken. Probably due to not being configured properly.
System	Uploader halted	CRITICAL SYSTEM FAILURE – no data will be sent to the cloud. If there is an SD card, CSV files will still be written and backlog data will be kept for when the uploader restarts. The uploader is halted by the configuration tool but should be running at all other times.

Interface is unresponsive

If the IoE Module interface becomes unresponsive (no longer responding to button presses), and stays that way for more than a few minutes, you can force the device to restart.

• Force power off: Press and hold the power button for 5 seconds. The IoE module will shut down inelegantly and open data files may be lost.

• Disconnect the power supply: As a last resort, if the none of the buttons are responsive, disconnect the power supply for 30 seconds to a minute. Reconnect the power and allow a few minutes for the device to start. If the unresponsive behavior persists, contact LI-COR.

Persistent power cycling or unstable behavior

If you observe continuous restarts or unpredictable behavior in the interface that is not resolved by restarting the device, you can take more drastic measures and restore the IoE Module to the factory configuration.

Before doing this, however, check the power supply to make sure the IoE module is getting enough power to operate. If the battery voltage is close to 11 volts, it may be too low and the battery should be charged before attempting a factory reset. Check the cellular signal strength. Although poor signal strength will not cause power cycling, it could cause delays in the interface, which are easily confused with unstable behavior.

After verifying that the problem is unrelated to power or signal strength, factory reset may be the best option. Factory reset will clear everything from the IoE Module except the factory provisioning data (cellular network, LI-COR Cloud services, security credentials, device serial number).

To perform the factory reset:

1. Power-off the device.

2. Press and hold UP and MOUNT/DISMOUNT simultaneously.

3. While UP and MOUNT/DISMOUNT are pressed, short-press the POWER button.

4. Continue to hold UP and MOUNT/DISMOUNT until the screen with the version info below the product name is displayed.

5. Release all buttons and allow the IoE module to finish starting up.

6. After resetting, you must re-configure SDI-12 sensors and schedules.

LI-COR Cloud issues

If you configured everything but do not see data on LI-COR Cloud, you may just need to wait at least 10 but possibly 30 or more minutes for results to be published. As you wait, you can check things on the IoE Module.

Check status of the IoE Module display. It is normal for several messages to be in the queue, but if there are many and the number is increasing over time, there may be an issue.

Check the SDI-12 configuration. From the home screen, press right once and down three times to select SDI-12. Press Select and the IoE Module will scan all SDI-12 ports and report the status. It will give Last Seen and the time of that communication. The time indicated should be recent, and if so, everything is working, and you should just wait for the data to be presented on LI-COR Cloud. See SDI-12 status for more details.

Finally, be sure that the IoE Module has been registered with LI-COR Cloud and that you have an account that allows you to view data from this IoE Module.