28 PS1000/2000 User Instructions
6 Serial Communication
6.1 Com Port 1
COM1 is a RS-232 bi-directional port. Communication wires are connected to the RS-
232 connector using TXD1, RXD1 and GND.
Table 6.1 PS-500 Com1 Port
NOTE: The indicator DB9 female connector has pin 4 and pin 6 shorted together.
Pin 7 and pin 8 are also shorted together.
6.2 Protocol
The baud rate and byte format is fixed by P5 and P6 settings.
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.
6.3 Transaction String
The length of the weight field will be 7 digits. One digit for minus sign, one for decimal
point, 2 for unit of measure.
l If the unit is lb:oz, another two for lb and on for a space after lb. Units of
measure abbreviations are always lower case.
l If the weight is over capacity, the scale will return nine "^" characters (the
field of minus sign, decimal point, weight data is filled by "^").
l If the weight is under capacity, it will return nine "_" characters (the field of
minus sign, decimal point, and weight data is filled by "_").
l If the zero point is error, it will return nine "_" characters. The character will
be “-” for negative weight or a space character for positive weight. Minus
sign follow after the first digit.
Useless leading 0 before digits is suppressed.
Designation Description Pin
TXD transmit 2
RXD receive 3
GND ground/common 5
DSR data set ready 4
DTR data terminal ready 6
CTS clear to send 7
RTS return to send 8
no connection no connection 1
no connection no connection 9
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