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
Line Feed character (hex 0AH)
Carriage Return character (hex 0DH)
End of Text character (hex 03H)
Space (hex 20H)
H
1
H
2
H
3
H
4
Four current status bytes
Polarity character: "-" or " "