T-Series WiFi Troubleshooting (App Note)

This troubleshooting guide provides tips to resolve issues with LabJack WiFi module connectivity.

It should be noted that WiFi is inherently less reliable than a wired connection. WiFi is often only suitable for lower acquisition rates, and if you can work around packets being dropped on occasion. Wired connections (USB/Ethernet) are recommended for the best connection reliability.

General Troubleshooting

If your device is associated to your network over WiFi but you are having problems after that, the most common reason is an issue with TCP configuration. See the general TCP troubleshooting tips in the Ethernet Troubleshooting App Note.
Check for updates to the LJM library and firmware (Device Updater tab in Kipling).
Close all software and use Ping to see if the device responds.
Realize that Kipling not showing a green button for the WiFi connection does not necessarily mean the WiFi connection is not working. It might just mean that the search used by Kipling can't find the connection, but a specific open does work fine. Try testing with Ping and TCPOpenTesting as outlined in the Setup WiFi and Ethernet App Note.
Update your access point with the latest firmware available from the manufacturer. It is very common for this to cause substantial improvement in the quality of a WiFi network.
Better reliability can sometimes be achieved with an external WiFi bridge module. See the Using a WiFi Bridge App Note.

Not Associated?

If you see an 'Association Failed' WiFi status when attempting to setup WiFi communications, see the following guidance:

Do your initial WiFi configuration using Kipling. See the Setup WiFi and Ethernet for T-Series App Note.
Note that SSID and password are both case-sensitive. Try re-configuring both values, ensuring that you have the correct values entered. Use a smart phone or Laptop to confirm the exact SSID name including capitalization.
Your network SSID and password must be alphanumeric. If necessary, change your access point network name and password to only letters and numbers. using only uppercase or lowercase letters can also help simplify setup.
Try disabling WiFi security on your access point. Note that with firmware 1.0225 and earlier a blank password will not work. Put in some characters even though security is off and no password is required.
What type of encryption is the network set to? WPA2-PSK (WPA2-Personal) is the most common, and seems to work the best. WEP encryption is problematic for the T7-Pro WiFi module.
The T7-Pro WiFi module does not support ad-hoc. For example, if you want to connect directly to a laptop, the laptop must be configured as an access point. See the "T7-Pro Direct to Computer via WiFi" section in the Basic Networking & Troubleshooting App Note.
The T7-Pro WiFi module is a 2.4 GHz b/g transceiver. The access point must support these frequency bands. On Wireless-N routers, it might help to disable the 5.8GHz operation of the router.
Connect to different networks to test whether the T7-Pro WiFi module is fine and the problem is with certain access points. See the “AP Troubleshooting” section in the Basic Networking & Troubleshooting App Note.

Signal Strength

Either a weak or excessively strong signal can lead to WiFi connectivity issues. A WIFI_RSSI value of -40 is very good signal strength, and -75 is very weak. We have found that an RSSI of -40 to -70 provides a good connection.

Note that when you read WIFI_RSSI from the T7-Pro you are reading the value stored on the main processor. The main processor gets an RSSI value from the WiFi module when it first joins a network, and then gets an updated value each time WiFi communication occurs. That means that if you are talking to the device over USB and no WiFi communication is happening, you will just keep reading the same initial RSSI value from joining.

Weak Wireless Signal Strength?

If possible, establish direct line of site from the LabJack antenna to your access point antenna. Otherwise, minimize the number of surfaces that the signal must pass through to reach each antenna.
Elevating the WiFi access point for your network can sometimes help improve signal coverage.
Consider using a better antenna with the LabJack. There is more information about antennas supported on T-Series devices in the WiFi section of the T-Series Datasheet.

Excessively Strong Wireless Signal Strength?

When signal strength gets stronger than -35, you may see more connection/transfer retries due to signal saturation, and the average time per iteration also increases. With the T7 and access point antennas touching each other you might see an RSSI of -10 and notice very poor communication.

LJLogM Testing

Use LJLogM to monitor WIFI_STATUS, WIFI_RSSI and VS (e.g. jumper any VS terminal to AIN0). Scale WIFI_STATUS by /1000 and WIFI_RSSI by /-10 so you can look at all 3 signals on the chart.

Log a file to send to support@labjack.com.
If you are having trouble joining your network, pay close attention to WIFI_STATUS. To get a meaningful WIFI_STATUS you need to connect to LJLogM over USB and set the LJLogM interval to 100 ms or less so you don't miss steps.
Note that WIFI_RSSI is only updated when WiFi communications on the LabJack occur. This means you must have an active connection to the LabJack WiFi for any meaningful WIFI_RSSI testing.

Checking Status Codes (`WIFI_STATUS`)

The status codes from WIFI_STATUS should typically change in the following sequence when connecting to a network:

WIFI_STATUS = 2904 for 3.8 seconds.
WIFI_STATUS = 2909 for 1.3 seconds.
WIFI_STATUS = 2906 for 0.9 seconds.
WIFI_STATUS = 2907 for 3.6 seconds.
WIFI_STATUS = 2900 continually, meaning the WiFi module associated to your network.

A network using a Linksys WRT54G access point (WPA2-Personal) and an Actiontec Q1000 router (DHCP server) was used for the following testing.

When the wrong WiFi password is used during setup, we found that the WIFI_STATUS sequence is 2904 for 3.8 seconds, 2909 for 1.3 seconds, 2906 for 10.0 seconds, then it starts over with 2904 again.

When WiFi security is then disabled on the access point, we found that the WIFI_STATUS sequence is 2904 for 3.8 seconds, 2909 for 1.3 seconds, 2906 for 0.2 seconds, 2907 for 3.6 seconds, and then 2900.

If you see WIFI_STATUS = 2900 but you still cannot talk to the device over WiFi, it suggests a general networking or TCP configuration issue. See the general TCP troubleshooting tips in the Ethernet Troubleshooting App Note.

Common Status Codes

The complete list of low-level WiFi status codes can be located in the T-Series datasheet, but the most common codes are listed below:

2900 → Associated
2902 → Association failed
2903 → Unpowered
2904 → Booting Up
2906 → Applying Settings
2907 → DHCP Started
2909 → Other

Survey WiFi Networks

Use another device with WiFi to do a site survey of all WiFi networks your area. This will show you what channels the different networks are using so you can make sure your network is using the best (clearest) channel. There are free apps for Android phones to do this, and also options for Linux/Mac/Windows.

Connection/Socket Traffic

The T7-Pro WiFi module only supports one socket for both discovery and normal communications. If you only have problems when there are multiple T7 applications running at the same time (e.g. Kipling and LJLogM) it could indicate that you are trying to use more socket connections than is supported. Similarly, since just one socket is used for both discovery and communications, external devices which send frequent UDP broadcast packets on the network could cause issues with WiFi module connection reliability.

Capture Network Traffic

Use Wireshark to get a capture of your network traffic while the problem is occurring, and send that capture to support@labjack.com.

Try Using a Different WiFi Channel

This is done in the settings on your access point as the access point determines what channel is being used.