Specifications

26
PIN DESCRIPTION
1 Protective Ground
2 Scale Receives Data
3 Scale Transmits Data
7 Protective Ground
It is necessary for the receive data pin of the external device to be connected to pin 3
(transmit data pin) of the scale. Likewise, the transmit data pin of the external device
must be connected to the receive data pin (pin 2) of the scale. With certain devices such
as computers with 9 pin serial ports (DB9), pins 2 and 3 must be "crossed." That is, pins
2 and 3 of the external device should be connected to pins 3 and 2 of the scale
respectively. Cables for this purpose are generally available from computer equipment
suppliers. Computers with 25 pin serial ports (DB25) generally require "straight" cables
to the Setra scale's RS-232 port.
NOTE: The “handshake” signals, such as RTS and CTS, are not implemented. This
requires that the peripheral have a minimal buffer (15 characters).
Use a mating connector (subminiature “D” type, female DB25-RJ45 converter to male
DB25-RJ45 converter) to gain access to these lines. The protective ground may be
attached to other grounds as deemed appropriate. This protective ground is available
at pin 1 and is connected to the chassis of the balance.
The maximum recommended cable length is 15 meters. The cable may be longer if it
has less than 2500 pF capacitance. The load impedance of the device connected
should be between 3000 and 7000 ohms with not more than 2500 pF shunt capacitance.
For more information, consult EIA Standard RS-232: “Interface Between Data Terminal
Equipment Employing Serial Data Interchange.”
In addition, some computers requiring handshaking will need a connection between
two pins on the computer’s connector named DTR and DSR (Data Terminal Reading
and Data Set Ready). CTS (Clear To Send) may also need to be jumpered to RTS
(Request To Send) at your computer interface.