Globalstar Product Management – Technical Support

Belkin F5U103 and F5U103-MAC Compatibility Issues (Improper HW Handshaking)

The Belkin USB Serial Adapter F5U103 does not provide proper hardware handshaking (CTS/RTS) prior to firmware version 2.06.

  • Hardware input flow control is only enabled for firmware levels above 2.06.
  • Hardware output flow control is working for all firmware versions.

Globalstar terminals use hardware flow control as the default flow control method for data communications. Belkin F5U103 adapters with firmware earlier than 2.06 do not provide proper hardware handshaking. Therefore, if you connect a Globalstar terminal to a Belkin F5U-103 Adapter that has firmware version lower than 2.06, you must do the following:

  1. Test F5U103:  Connect to the Globalstar device via a simple TTY interface (e.g., HyperTerminal or MTTTY), and issue some AT modem commands, such as:
    a)  AT
    b) ATI
    c) ATZ
  2. If you are NOT able to issue any AT commands, or if you don’t receive any response from the modem:
    a) Double check your baud settings on the computer and on the Globalstar device to make sure that they match
    b) If you are still unable to communicate with the Globalstar device using AT commands, you will have to Jumper pins 7-8 of the DB9 to bypass hardware handshaking, and falsely indicate to the Globalstar terminal that hardware flow control (CTS/RTS) is working.
  3. Change Flow Control Method of Globalstar Terminal:  Issue one of the following AT commands to the Globalstar terminal to make the terminal use a different form of flow control than hardware flow control:
    a) AT+IFC=1,1     ==>  for Software Flow Control
    b) AT+IFC=0,0     ==>  for No Flow Control
  4. Modem Resets to Defaults:  For all Globalstar terminals (except for the GSP-1700 and GSP-1720), the flow control method will be reset to Hardware flow control whenever the Globalstar terminal is rebooted or reset. Therefore, the AT+IFC command should be part of the modem initialization string that is issued before every data communication session.
  5. Saving Modem Defaults (only for GSP-17xx):  For the GSP-1700 and GSP-1720, the flow control settings can be saved into the default settings for the Globalstar terminal so that the new flow control settings will be used whenever the Globalstar terminal reboots.

Additional Keywords:  USB-to-Serial

Written by Joseph Crowley

May 30, 2017 at 11:09 am

Posted in Uncategorized

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