Measurement Technology NW
LCI-90 Operator Manual
Page 48
6.6.4 Protocol descriptions
The data transmitted through the AUX port contains (usually) values for Tension,
Payout and Speed (sometimes known by other names). The format of this data is
determined by the "protocol" selected. The LCI-90 currently supports four protocols,
numbered: 0, 1, 2, 3. Protocol '0' is a special 'diagnostic' protocol that is normally
only used during production.
Protocol '1' is the LCI-90’s Remote Data protocol. This format is the same one used
to send data to Remote Displays over the network communications port; it is a check-
summed, comma-separated, maximum precision, zero-filled format, consisting of
strings with the form:
"RD,–TTTTT.TT,–SSSS.SSS,–PPP.PPPP,CCCC<CR><LF>"
where "RD" identifies the record as a Remote Data string, "–" stands for an optional
minus sign, which is always the first character (but omitted if the data is positive).
"TTT" is the Tension, "SSS" is the Speed, and "PPP" is the Payout. Each field is 8
characters long, with leading '0's as needed. The indicated decimal points are only
symbolic – integer values will not have a decimal point, and the number of digits
following the decimal point (if any) is adjusted on a record-by-record basis to reflect
the internal accuracy of the data.
Programs written to parse these strings should look for the commas. (Excel calls this
a 'CSV', Comma Separated Values, format). "CCCC" is a 4-digit (always!) decimal
field, which contains the sum of the ASCII values of all preceding characters, inclu-
ding the commas (but not including the four CCCC characters). All characters
included in the sum have ASCII values less than 127, hence it will not matter if the
receiving device uses "7-bit" or "8-bit" characters. Spurious characters preceding
"RD" may occur, and should be ignored. Each record ends with a Carriage Return
(ASCII 13) + Line Feed (ASCII 10), which are not included in the checksum.
Protocols '2' and '3' consist of strings with the general form:
"xx00_TTTTTTT_0_PPPPPPP_0_SSSSSSS_0<CR><LF>"
where "TTT", "PPP" and "SSS" are 7-character (including sign and decimal point)
strings for the Tension, Payout and Speed values. The number of decimal places is
determined by the configuration setting for the respective displays (see §5.10.3).
Minus signs (if any) appear just before the first significant digit, with the remainder
of the field filled with spaces (ASCII 32). The first two characters, "xx", are "**"
(two stars) for Protocol #2, and "<CR><LF>" (Carriage Return, Line Feed) for Pro-
tocol #3. This is followed by "00" (two ‘zeros’), then either a SPACE (Protocol #2)
or a COMMA (Protocol #3), seven characters for the Tension, a SPACE or COMMA
(represented by "_"), then a "0" (zero), and so on for Payout and Speed. The string
ends with a Carriage Return (ASCII 13) and Line Feed (ASCII 10).
Additional, or alternative, protocols can be supported. Contact Measurement Tech-
nology NW for advice on this matter.
