Salter Brecknell 6700U Series (USB) - Manual (Page 62)

62 67XXU USB/Serial Scale Service Manual
7.2 Com Port 1
COM1 is a USB port used as a virtual RS-232 port. Communication wires come from
the USB connector and TXD0, RXD0 and GND.
7.3 Com Port 2
COM2 is a RS-232 bi-directional port. Communication wires are connected to the RS-
232 connector using TXD1, RXD1 and GND. Refer to
page 19 for connection details.
7.4 Protocol
The baud rate and byte format is set by USER-COM-BUD.RT and USER-COM-
BT.FMT.
Responses to serial commands will be immediate or within one weight measure cycle
of the scale. One second should be adequate for use as a time-out value by remote
(controlling) device.
7.5 Transaction String
The length of each item in a transition string:
l
Reading data --- 6 bytes
l
Data polarity ----1 byte: "-" for negative, and followed the first digit; " " for
positive.
l
Decimal point ---1 byte: "."
l
Measure unit ----1-5 bytes:" lb"," kg","lb:oz","pcs","%". Units are always
lower case, left aligned
l
Current status-- 4 bytes
m
If the weight is over capacity, the scale will return eight "^" characters
(the field of polarity, decimal point, weight data is filled by "^").
m
If the weight is under capacity, it will return eight "_" characters (the field
of polarity, decimal point, and weight data is filled by "_").
m
If the zero point is error, it will return eight "-" characters (the field of
polarity, decimal point, and weight data is filled by "-").
Useless leading 0 before digits is suppressed. Reading weight is right aligned.
Table 7.1 Symbols Used
<LF> Line Feed character (hex 0AH)
<CR> Carriage Return character (hex 0DH)
<ETX> End of Text character (hex 03H)
<SP> Space (hex 20H)
H
1
H
2
H
3
H
4
Four current status bytes
<P> Polarity character: "-" or " "