From Technologic Systems Manuals

The XBEE header is intended for Digi XBEE modules, or Nimbelink's Skywire embedded modems.

For XBEE modules, these will use 3.3V and require USB to be disabled:

# Enable 3.3V
gpioset 7 6=0

# Turn off USB
gpioset 7 9=0

# Access /dev/ttymxc3

Nimbelink modules require settings for the specific modems. Verify in the datasheet of the modem appropriate for your cell network to determine if the module uses USB. If not, verify the expected serial baud rate and settings. Some modems need 3.3V power, and some modems expect a typical of 4V.

# For modules wanting 4V:
gpioset 7 6=1

# For modules wanting 3.3V:
gpioset 7 6=0

# Power can be turned off if this GPIO is configured as an input
# gpioget 7 6

# If your modem supports USB, this must be enabled.
gpioset 7 9=1
Note: Some Nimbelink cell modems have a long startup and may not show up on USB for a minute before enumerating on USB.

Serial based modems can be tested with picocom

# Verify the baud rate for your specific modem
picocom -b 921600 /dev/ttymxc3

With picocom type "AT" and press enter and it should return "OK". Press Ctrl+a+x to close picocom.

Pin Description
11 GND
12 /dev/ttymxc3 CTS
13 NC
14 3.3V
15 GND
16 GND
17 NC
18 NC
19 NC
20 GND
TS-7100 Nimbelink.png
Pin Description
10 GND
8 USB-
7 USB+
6 4.7V
5 NC
3 /dev/ttymxc3 TXD
2 /dev/ttymxc3 RXD
1 NIMBEL_PWR (3.3V or 4V)

While pin 1 commonly lines up with the antennas on the modems, the pin 1 orientation should be verified in your modem's datasheet.