Gentec-EO T-Rad (DB-15) - Manual (Page 15)

T-RAD-DB15--USB Instruction Manual Version 2.1 December. 2012 15
Figure 8 Phase Specific Detector Output Signal
The multiplier action moves the signal to the frequencies at the sum and difference of the signal
and the reference frequency at 25Hz. Therefore the signal at 25Hz will move to 0Hz and 50Hz, as
seen. The 60Hz interference will move to 85Hz and -35Hz, not shown here. The odd harmonic of
the input signal at 75Hz moved to 100Hz and 50Hz, where it will add to the frequency shifted
signal. These signals can now be low pass filtered to extract the DC component.
1.3 Communications with Host PC
The T-RAD communicates with the host PC via a USB port. The device supports full speed USB
2.0. The implementation of the port in the host PC is accomplished via a Virtual Com Port, or
VCP. This in effect mimics a standard com port so that the user can take advantage of the ease
of developing custom applications with existing terminal emulators.
The Ports Settings are:
Baud Rate: 921600
Data Bits: 8
Stop Bits: 1
Parity: None
Flow Control: None
If the host PC cannot supply a baud rate of 921600, the T -Rad will adjust its baud rate to match
the fastest one available from the PC. The host PC must have a terminal emulator as well as the
T-RAD USB drivers installed. These drivers are installed by the disc supplied with the T-RAD
instrument.
The command set for the T-RAD instrument is shown below.
All commands and replies are followed by a carriage return (0x0D) and a line feed (0x0A). If a command is
used with no arguments it will become a query.
All commands except STR1 reply with:
Ok if the command executed correctly.
Err if the command could not be executed.
All Queries reply with the item that was queried or Err if the query could not be executed.
With the exception noted above, the host software should wait for an instrument reply before executing a
subsequent command or query.