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LaserLT-60 and LaserLT-100 Large-Display Weight Indicators
6.0
Communications
This section provides an overview of LaserLT-60 and LaserLT-100 Weight Indicator communication information.
6.1
Serial Outputs
The instrument has two bidirectional serial outputs which are ASCII code compatible with most printers, remote displays, PCs
and other devices. See
Section 2.2 on page 5
Transmission of data through the serial ports can be configured in the parameters PC SEL, PCModE and Pr.ModE in the setup
mode
(Section 6.2 on page
39).
6.1.1
COM1 Serial Port
The COM1 serial port is bi-directional (half duplex) and uses RS-485 for transmitting data. It is mainly used to connect PCs,
PLCs and additional remote displays. The transmission speed may be selected in the setup as: 1200, 2400, 4800, 9600,
19200, 38400, 57600, 115200 baud (bit/sec).
On the same RS-485 line, it is possible to connect up to 32 devices (instruments, RS-485/RS-232 signal converter).
Considerations when making RS-485 connections:
• Use a Shielded Twisted Pair cable to make the connection (twisted and shielded pair(s) with single shielding for each
pair through aluminum band and total shielding through external shielding)
• Using 2x24 AWG duplex cable with external shielding, the RS-485 cable should not exceed 4000' (1200 m)
on page
51)
• With very long cables, cable capacity becomes a dominant factor in power consumption (normally near 50pF/m); Cable
capacity decreases as length increases; Capacity also decreases when speed is increased; The maximum distance
cannot be covered with the maximum possible speed
• Verify single point grounding on all equipment
• 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; Terminal resistance is not supplied with the ports of the
instrument
• Consult the device product data sheet for all connected devices to ensure consistency in the markings
6.1.2
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.
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for connection information.
Baud Rate (bit/sec)
Total Cable Capacity (pF)
1200
2400
4800
9600
19200
38400
57600
115200
Table 6-1. Cable Capacity
(Section 2.1 on page
400000
200000
100000
50000
25000
12000
8000
4000
5)
(Section 8.0
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