Salter Brecknell WB-521 Series - Manual (Page 61)

SBI521 Service Manual 59
6 Serial Communication
6.1 Com Port 1
COM1 is a RS-232 bid-directional port. Communication wires are connected to the RS-
232 connector using TXD1, RXD1 and GND. Refer to
page 9 for connection details.
6.2 Com Port 2
COM2 can be RS232 or RS485, if used as RS232, communication wires come from
RS232 connector, and TXD2, RXD2 and GND are used, if used as RS485,
communication wires come from RS485 connector, and A and B are used (if need GND
or +5VCC1 can be used).
Please refer to page 9 for jumper connector details.
6.3 Protocol
The baud rate and byte format is set by USER-COM1/2-BAUD.RT and USER-COM1/
2-BYT.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.
6.4 Transaction String
The length of each item in a transition string:
l
Reading data --- 6bytes
l
Data polarity ----1byte: "-" for negative, and followed the first digit; " " for
positive.
l
Decimal point ---1byte: "."
l
Measure unit ----1-5bytes:" lb"," kg","lb:oz","pcs","%". Units are always lower
case, left aligned
l
Current status-- 4bytes
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.