Epson XDT manual Appendix K RS-232C Interface Protocol, Help command

XDT User’s Manual Appendices

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 XDT. Receive refers to receiving from the XDT into the host computer. The com- mands 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 ESC, this signifies a single byte (hex 1B). Optional characters or command argu- ments 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]CR

receive: Help	?	Data	SN	C L
				R F
Who	Reset	Login	C L
			R 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: DA[TA] units [interval [mode]]CR

C	nn	N
F		G
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 H20/mmscf and gm/m3 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 255 seconds. This feature allows the user to log the measurement on a dumb terminal or a printer.

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