NARDA PMM 6600, User Manual

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Serial Communication Protocol 5-1
5 - Serial Communication Protocol
5.1 RS 232 Protocol
A reading of the measured RF power levels through any different software
application can be also available using the following specifications to
communicate via RS 232 with the 6600 Power Meter:
•
the communication is asynchronous and half duplex, where the
computer is the master and the 6600 can only be the slave
•
the Baud Rate is 9600 with 8 bit for each string, 1 stop bit and no parity
bit
•
the length of the strings is fixed, using the usual ASCII code from 00 to
127 (8FH); in dual configuration 6600+6600D, each string of the
Primary unit (6600) starts with “
#PM ” and ends with “ * ”; instead, each
string of the Secondary unit (6600D) starts with “ #SM ” and ends with
“ * ”.
By now the RF Power meter recognises up to 3 requests sent by the
computer:
#PMV*
#SMV*
to know type and firmware release number of the
instrument;
For the Primary unit, the answer is “
PMM6600 Vx ”, where
“ x ” is the firmware release
#PMp*
#SMp*
the answer are 2 bytes ( H , the first transmitted, and L ) to
calculate the measured CW power (without modulation)
#PMP*
#SMP* the answer are 2 bytes ( H , the first transmitted, and L ) to
calculate the measured modulated power
5.2 Calculation of Power
The Power P have to be calculated as per the following formula:
Example:
At the enquiry “ #Pmp “ the 6600 answers “ 03H ” and “ 3FH” (3 and 63 in
decimal), then the CW power (or the power without modulation correction)
is
Document 6600EN-00705-1.10 -
© NARDA 2007
P
H L
=
∗ + −
( ) 256 1000
10
P dBm
=
∗ + −
= −
( )
,
3 256 63 1000
10
16 9