User Manual

Page 8 of 9
Appendix: Technical Background
The following are excerpts from the Wireless MiniTerm Developers Manual. This
information is provided here to help the system integrator to understand how the
unit operated.
Wireless -- (8:1)
In 8:1 systems the keypad is configured as a slave and the dongle is configured
as master. The host dongle is continually polling for Mini-Terms but one or more
of them may be missing or sleeping at any given time.
Virtual Serial Over USB (HID)
It is worth noting a few points regarding how virtual serial differs from traditional
RS232. First of all, the driver on the host (PC) is not loaded into memory until the
USB device is plugged in. With traditional RS232 one could open a COM port at
any time, regardless of whether the target device is attached or not. With USB
this is not the case. If the Wireless Mini-Term dongle is not plugged in, attempts
to open the COM port will fail. Unplugging and re-plugging a Wireless Mini-Term
dongle will usually require that the COM port be closed and reopened. Opening
the COM port only pertains to the dongle. Whether any given remote keypad is
awake or sleeping, turned on or turned off, does not affect the ability to open a
COM port. USB transfers all of its data in 8-bit format (no parity) and utilizes the
USB spec CRC checksums for error detection. As a result your host port settings
(baud rate and word format) do not matter over USB.