Operating instructions

8800 Series Trace Moisture Analyzer Instruction Manual Appendices
52
Appendix K: RS-232C Interface Protocol
The instrument uses a simple protocol to communicate to a host computer through its RS-232C
interface, see section 3.3.2.5 for electrical connections. The interface is configured as 9600 baud,
Even Parity, 8 Bits, 1 Stop; and it echoes all received characters.
To illustrate the protocol, the following notation conventions are used in this section:
The characters sent or received are depicted in bold. Send refers to sending from the host com-
puter to the 8800 Series Trace Moisture Analyzer. Receive refers to receiving from the 8800
Series Trace Moisture Analyzer into the host computer. The commands and arguments are shown
in capital letters while place holders for choices are labeled with lowercase italic letters, with the
allowed characters shown below, “nn” denotes a numeric value. Bytes which are not characters
are shown with diagonally placed mnemonics, for example Escape is depicted as
E
S
C
, this signi-
fies a single byte (hex 1B). Optional characters or command arguments are encompassed with
brackets [ ].
The commands may be sent in either upper or lower case. Arguments may be delimited with
space or comma.
HELP command
Lists all of the available commands.
send: H[ELP]
C
R
receive: Help ? Data SN
C
R
L
F
Who Reset Login
C
R
L
F
DATA command
Selects the reporting format of the current measurement.
This formatting will be retained until the next DATA command even if the power is turned off.
send: D[ATA] units [interval [mode]]
C
R
CnnN
FG
P
L
G
D
U
The units argument selects the units in which the measurement will be reported.
C,F,P,L & G select the dewpoint in °C,°F,ppm,Lbs H
2
0/mmscf and gm/m
3
respectively.
D selects decibels which is the measured sensor attenuation.
U selects using whatever units are selected by the user on the display.
The interval argument is optional, if it is not entered then the measurement will be reported only
on a query with the “?” command. However if it is desired for the unit to report the measurement
on a regular interval without a query then an interval in seconds may be specified in the range 1 to