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Software & Driver

 

7.0 WiFi (T7 only) [T-Series Datasheet]

Overview - T7-Pro Only

Communication Protocol: Modbus TCP

Connector Type: Female RP-SMA

Transceiver: 2.4 GHz 802.11 b/g (Compatible with ac, and n routers)

Security:  None or WPA2-PSK (WPA2-Personal)

Range: Similar to laptops and other WiFi devices with stock antenna 

Max Packet Size: 500 bytes/packet

The T7-Pro has a wireless module. Refer to this WiFi and Ethernet tutorial to get started.

DHCP is enabled from the factory, so to get WiFi going from the factory write the desired SSID string (case sensitive) to WIFI_SSID_DEFAULT and the proper password string (case sensitive) to WIFI_PASSWORD_DEFAULT. Then write a 1 to WIFI_APPLY_SETTINGS and watch the status codes. If you get back code 2900 the WiFi chip is associated to your network, and you can then read the assigned IP from WIFI_IP.  Find more details and troubleshooting tips in the WiFi and Ethernet tutorial.

Data Speed: It's possible to get data faster on a T7-Pro using its Ethernet interface instead of its WiFi interface, both for command response and streaming modes. Wireless bridges and access points do not introduce a speed bottleneck, so a bridge is a good way to get fast wireless data from any T-series device. See the Convert Ethernet to WiFi App Note for setup information.

Port

The T7's WiFi module responds to connections or packets on port 502 for both UDP and TCP.

Config (_DEFAULT) Registers

Use the following _DEFAULT registers to configure WiFi:

WiFi Config Registers
Name Start Address Type Access

WIFI_IP_DEFAULT             The new IP address of WiFi. Use WIFI_APPLY_SETTINGS.

49250 UINT32 R/W

WIFI_SUBNET_DEFAULT             The new subnet of WiFi. Use WIFI_APPLY_SETTINGS.

49252 UINT32 R/W

WIFI_GATEWAY_DEFAULT             The new gateway of WiFi. Use WIFI_APPLY_SETTINGS.

49254 UINT32 R/W

WIFI_DHCP_ENABLE_DEFAULT             The new Enabled/Disabled state of WiFi DHCP. Use WIFI_APPLY_SETTINGS

49260 UINT16 R/W

WIFI_SSID_DEFAULT             The new SSID (network name) of WiFi. Use WIFI_APPLY_SETTINGS.

49325 STRING R/W

WIFI_PASSWORD_DEFAULT             Write the password for the WiFi network, then use WIFI_APPLY_SETTINGS.

49350 STRING W

WIFI_APPLY_SETTINGS             Apply all new WiFi settings: IP, Subnet, Gateway, DHCP, SSID, Password. 1=Apply

49400 UINT32 W

These registers can also be read, except WIFI_PASSWORD_DEFAULT.  Configure the WiFi network configurations in Kipling software.

These _DEFAULT registers are non-volatile.  Whatever value you write to a _DEFAULT register will be retained through a reboot or power-cycle.  New values written to these _DEFAULT registers are not applied until power-up or until a 1 is written to WIFI_APPLY_SETTINGS.

Status Registers

Use the following read-only registers to read the status of WiFi:

WiFi Status Registers
Name Start Address Type Access

WIFI_IP             Read the current IP address of WiFi.

49200 UINT32 R

WIFI_SUBNET             Read the current subnet of WiFi.

49202 UINT32 R

WIFI_GATEWAY             Read the current gateway of WiFi.

49204 UINT32 R

WIFI_DHCP_ENABLE             Read the current Enabled/Disabled state of WiFi DHCP.

49210 UINT16 R

WIFI_SSID             Read the current SSID (network name) of WiFi

49300 STRING R

WIFI_STATUS             Status Codes: ASSOCIATED = 2900, ASSOCIATING = 2901, ASSOCIATION_FAILED = 2902, UNPOWERED = 2903, BOOTING = 2904, START_FAILED = 2905, APPLYING_SETTINGS = 2906, DHCP_STARTED = 2907, OTHER = 2909

49450 UINT32 R

WIFI_RSSI             WiFi RSSI (signal strength). Typical values are -40 for very good, and -75 for very weak. The T7 microcontroller only gets a new RSSI value from the WiFi module when WiFi communication occurs.

49452 FLOAT32 R

Config (_DEFAULT) vs. Status Registers

Example: If you write WIFI_IP_DEFAULT="192.168.1.208" (you actually write/read the 32-bit numeric equivalent—not an IP string), then that value will be retained through reboots and is the default IP address.  If DHCP is disabled, this will be the static IP of the device and what you get if you read WIFI_IP.  If DHCP is enabled, then a read of WIFI_IP will return the IP set by the DHCP server. 

Power

The following registers configure WiFi power:

WiFi Power Registers
Name Start Address Type Access

POWER_WIFI             The current ON/OFF state of the WiFi module.

48004 UINT16 R/W

POWER_WIFI_DEFAULT             The ON/OFF state of the WiFi module after a power-cycle to the device. Provided to optionally reduce power consumption.

48054 UINT16 R/W

Examples

Read IP Example: To read the wireless IP address of a device, perform a Modbus read of address 49200.  The value will be returned as an unsigned 32-bit number, such as 3232235691.  Change this number to an IP address by converting each binary group to an octet, and adding decimal points as necessary.  The result in this case would be "192.168.0.171"

Write IP Example: To change the Wireless IP Address of a device, perform a Modbus write to address 49250.  The IP address must be passed as an unsigned 32-bit number, such as 3232235691.  Change this IP address "192.168.0.171" by converting each octet to a binary group, and sticking them together. 

Antenna Details

The T7-Pro ships with a standard RP-SMA 2.4 GHz antenna similar to the W1030, or the A24-HASM-450.  To put an antenna further away from the T7-Pro you can use any standard male-female RP-SMA WiFi extension cable.

The connection to the WiFi module on the T7-Pro PCB is made via a snap-on/snap-off ultra miniature coaxial connector called male U.FL (aka AMC, IPEX, IPAX, IPX, MHF, UMC or UMCC).  The normal T7-Pro uses a U.FL to bulkhead RP-SMA cable with a length of 140mm, similar to the Taoglas Limited CAB.622Emerson 415-0100-150, Laird 1300-00041, Amphenol 336306-14-0150, or Amphenol 336306-12-0150.

To search for U.FL to RP-SMA cable options at Digi-Key, go to the "Cable Assemblies => Coaxial Cables (RF)" section, and filter by Style = "RP-SMA to IPX" or "RP-SMA to MHF1" or "RP-SMA to UMC" or "RP-SMA to UMCC".  Then look at the picture and make sure it looks correct, as the application of the terms "male" and "female" are not totally standardized.

T7-Pro-OEM ships with a simple 30mm U.FL whip antenna such as the Anaren 66089-2406.

WiFi Range

The WiFi range on the T7 is typical for a modern WiFi device. In direct line-of-sight with the router, it's possible to get a decent connection at 100m. The table below shows signal strength at varying distances with a stock T7 antenna, and a simple WiFi router. Both the T7 and the router were positioned 3ft off of the ground, with direct line-of-sight.

Distance RSSI
10m -44dBm
25m -45dBm
50m -55dBm
100m -59dBm

During testing, it was noted that the T7 had slightly better WiFi range than an HTC One V cell phone. The WiFi signal is spotty at RSSI lower than -75dBm, and the connection will cut off entirely around -80dBm. Note that 90° antenna orientation was used in testing above. That is to say, keep the antenna in the fully bent upright position, don't try to point it at the router, or accidentally leave it at 45° bent. At 45° bent, or directly pointed towards the router, the signal strength is reduced by about 5dBm.

Note that the RSSI value you can read (WIFI_RSSI) is only updated when WiFi communication occurs.  That is, if you talk to the T7 over USB to read the RSSI value, you will just get the value from the last WiFi communication that occurred.

OEM Whip Antenna

The OEM whip antenna is a short segment of wire, only 30mm in length. This whip antenna provides an inexpensive solution for adding WiFi to an OEM board, without the need to figure out mounting of a bigger antenna. The signal strength of a 30mm whip antenna is on average 11dB less than that of the stock antenna. The table below demonstrates the 30mm antenna signal strength at various distances.

Distance RSSI
10m -49dBm
25m -58dBm
50m -70dBm
100m -73dBm

Improve signal strength

The first step to improve the signal strength at large distances is to insure direct line-of-sight. Beyond that, the next best thing is to elevate the transmitter and receiver antennas. Even an elevation of 1m off the ground helps quite a bit. Be sure to consider the probability of lightning strikes if the antenna is high relative to the surroundings.

The next step to improve signal strength is to use a directional WiFi antenna. Directional antennas improve range substantially, such that even a homemade solution can increase range to fifteen times that of a non-directional antenna. If you need something to work at 500m, it's possible to buy a simple yagi antenna for $60 USD approx.

Network Schemes

Figure 1 demonstrates a basic network diagram where the T7-Pro is connected to the "Office WiFi" network. The T7-Pro can be controlled by either host option (1 or 2). For much more information on Ethernet and WiFi networking see the Basic Networking & Troubleshooting App Note.

Figure 1. Most common configuration for a home, or small office network.