Red Lion LEGEND - Manual (Page 34)

SENDING COMMANDS AND DATA (Cont’d)
It is recommended that a “Transmit Value” command follow a “Change
Value” Command. If this is done, the reception of the data can provide a
timing reference for sending another command and will insure that the
change has occurred. When a “Change Value or Reset Value” command is
sent to the Legend, there is time required for the unit to process the command
string. The diagrams show the timing considerations that need to be made.
RECEIVING DATA
Data is transmitted from the Legend when a “T” Transmit Value or a “P”
Transmit Print Options command is sent to the Legend via the serial port or
when a User Input, programmed for the Print Request function, is activated.
The Legend will wait until the serial transmit delay (0.100 or 0.002 sec) time
expires and then begin transmissions. The Legend can be programmed to
transmit Mnemonics. The format for a typical transmission string with
mnemonics is shown below:
The first two digits transmitted are the unit address followed by one blank
space. If the unit address is 0, the first locations will be left blank. The next
three characters are the mnemonics followed by one or more blank spaces.
The numerical data value is transmitted next. Negative values are indicated
by a “-” sign. If the numeric value is in an Overflow condition an asterisk (*)
will precede the most significant digit of the value. The decimal point
position will “float” within the data field depending on the actual value it
represents. The numeric data is right justified without leading zeros.
When a “T” command or print request is issued, the above character string
is sent for each line of a block transmission. An extra < SP> < CR> < LF> is
transmitted following the last line of transmission from a print request to
provide separation between print outs.
If Mnemonics are NOT transmitted, just numeric data is sent with no built-in
time delay. If the Legend transmits Mnemonics, there is a 400 msec built-in time
delay after each transmission string. When interfacing to a printer, sending
Mnemonics are usually desirable. Examples of transmissions are shown below:
3 CNT -6732.5< CR> < LF> (400 msec delay) Mnemonics Sent
-6732.5< CR> < LF> NO Mnemonics Sent
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