Troubleshooting

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

Connection issues

Most connection issues can be resolved by checking the wiring connections, address of the LI-710, or the data logger configuration.

• No data or unexpected replies?
• Check the power wires. Be sure the black lead is connected to ground and the brown one is connected to a 9 to 33 VDC supply. When it is on, you can hear the pump running quietly and faint clicks near the sonic transducers. If you don't hear the LI-710 running, investigate the power supply. If it is running, continue with the next steps.
• Data wire attached?
• Check the blue data wire. Be sure it is connected to an SDI-12 terminal, and that the terminal is configured to support the SDI-12 protocol.
• Wrong address applied to sensor or specified in the program?
• Check the LI-710 address. Using the command-line interface provided in your data logger program, request information by sending "?!", along with the syntax required by your data logger. The LI-710 should respond with information, including the current address. You can send a command to change the address if needed.
• Address conflicts with multiple LI-710s or other devices?
• Each SDI-12 device connected to the terminals must have a unique address. Connect each device to the terminals one at a time and query each one for its address. If you find any conflicting addresses, make changes so each one is unique. You may also need to update the datalogger programs to reflect the new device addresses.

Power issues

The LI-710 requires 1.5 watts during normal operation. When power is first supplied, it may draw up to 24.6 watts for 20 milliseconds. Some SDI-12 power supplies are current-limited and unable to provide sufficient power to satisfy the startup requirements, leading to continuous reboots or the delivery of partial data. If you observe either of the two conditions, connect the brown (+) and black (-) wires directly to the data logger power supply (9 to 33 VDC) and power it back on.

Diagnostics

Before computing any results, the LI-710 filters implausible values from the 10 Hz raw data. You can see how many were included in a measurement period in the eighth parameter of group 1 (Group 1: Results and sample count), and the percent used as the eighth parameter of group 3 (Group 3: Performance information and diagnostics).

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-710 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 9‑1.

Table 9‑1. A diagnostic code is included with each measurement. A DEC value of 0 indicates normal operation.

Bit Position	DEC	Description	Threshold
-	0	Normal operation	No issues reported
0	1	Flow out of range	Average flow for a 30-minute period is <125 sccm or >330 sccm
1	2	Reserved	Not applicable
2	4	Reserved	Not applicable
3	8	Low RH sensor voltage	Voltage ≤1.6 V for >50% of time for a 30-minute period
4	16	Cell temperature out of range	>65 °C or <-50 °C for >5% of time for a 30-minute period
5	32	Reserved	Not applicable
6	64	No sonic	Sonic anemometer is not detected
7	128	Poor sonic signal	Poor sonic signals persist for >10% of time for a 30-minute period
8	256	Rain detected	True for >50% of time for a 30-minute period
9	512	High humidity shutdown	>90% cell RH >2 data points or >90% ambient RH for 100 data points and 50% of the last 100 sonic rain flag data points
10	1024	Cold temperature shutdown	Cell temperature <0 °C for 100 data points
11	2048	High cell pressure relative to ambient	Average cell pressure - average ambient pressure is > 0.4 kPa for a 30-minute period
12	4096	Low cell pressure relative to ambient	Average cell pressure - average ambient Pressure is < -1.5 kPa for a 30-minute period
13	8192	Reserved	Not applicable
14	16384	Low pump voltage	Pump voltage <8 V for >50% of time for a 30-minute period
15	32768	High pump voltage	Pump voltage >20 V for >50% of time for a 30-minute period

Interpreting and responding to the diagnostic

Diagnostics presents themselves in combinations that can be reduced to a cause and solved. Table 9‑2 presents bit positions and combinations, possible scenarios, and potential solutions.

Table 9‑2. Bit positions and combinations can be interpreted and resolved by maintenance, or sometimes, just waiting.

Bit Position
and	or	or	or	Scenario	Solution 1	Solution 2	Solution 3
0, 15	12			Intake clogged by dust	Replace filter1
0, 15	12			Exhaust clogged (unlikely)	Clean exhaust screen2
0, 15	12	9	7	Intake clogged by water and/or dust (unlikely)	Replace filter1	Wait for system to dry
0, 15	9			Condensation on filter3	Wait for filter to dry	Replace filter1
0, 15	11	12		Leak in pump stack	Check O-rings, replace if damaged4	Replace pump4
14				Intake leaking	Replace filter1
15				Intake clogged	Replace filter1
0, 9	15	35		Flow path has water inside	Wait for system to dry	Replace pump4
10				Instrument temperature too low; pump disabled	Wait for ambient temperature to rise
7, 8	9	0		It is raining outside	Wait for rain to stop	Wait for filter to dry	Wait for system to dry