Rice Lake SCT-1100, Technical Manual

Page: 59 / 88

Communications 55
• Verify single point grounding on all equipment. See Section 2.4 on page 8 .
• Use correct single point grounding to avoid forming ground loops.
• On the RS-485 network, two termination resistances equal to the impedance of the cable (typically 120
Ω )
are normally connected on the two devices at the ends of the cable. The terminal resistance is not supplied
with the ports of the instrument.
• The difference of potential between the A(+) and B(-) terminals in rest conditions must be of at least 0.2 V.
To create a resistive divider which maintains this difference of potential also when all the transmitters are
disabled, inert in the RS-485 port of the instrument where there are the termination resistances, the
polarization or fail-safe resistance. The value of these resistances is between 390 Ω and 2.2K Ω .
• Consult the device product data sheet for all connected devices to ensure consistency in the markings.
6.2.2 COM2 Serial Port
The COM2 serial port is bi-directional (full duplex) and uses an RS-232 for transmitting data. It is mainly used to
connect printers, PCs, and PLCs. The transmission speed may be selected in the setup as: 1200, 2400, 4800, 9600,
19200, 38400, 57600, 115200 baud.
6.3 Serial Port Transmission Modes
6.3.1 PC Port Selection
It's possible to select the serial port to be used as a PC port and therefore, invert the serial ports.
This setting is made in the




 step.
Select the RS-485 serial port as the PC PORT and the RS-232 serial port sets as the PRN PORT.
Select the RS-232 serial port as the PC PORT and the RS-485 port sets as the PRN PORT.
6.3.2 PC PORT
This section described the selectable serial weigh transmission modes of the PC serial port.
Figure 6-2. PC Port Menu
Parameter Description

Transmission requested from an external device – The instrument waits for a command before transmitting
data; See
Section 6.4 on page 57
With baud rate at 9600, up to 10-11 requests per second are possible through the READ command; with baud
rate at 115200, up to16 requests per second are possible through the READ command;
The transmission works with weight <, =, > 0


For manufacturer use only;
Selecting a functioning mode other than

in
  
,
the weight display occurs both in the instru-
ment, as well as in a weight repeater of 4 or 6 digits.
Table 6-5. PC Port Parameters
&R03& 3&0RG(
E$XG
(!) , , , ,
, , ,
(!)
RQG(
,
U(3(
,
U(3(
,
3ULQ6W
,
3ULQ(;
, ,
0RGEX6
,
,
$// 0$;
,
$//6WG
,
$//([W
,
6W$E6W
,
6W$E(;
,
:U(3(
( § ) ,
3U
( § ) ,
U(3(G&
( § ) ,
U(3(LQ
( § ) ,
$U(3(
( § )
ELW
Q
,
Q
,
Q
,
(
,
(
6(WX3
)/GEXV