| There're 2 RS-232 serial ports in a PC. How to increase more RS-232 ports? |
| You may add a multiport board to increase the number of serial ports, generally called COM port, on your system. |
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| There are 2 RS-232 serial ports and are not RS-422 or RS-485 ports in a PC. How to set RS-422 or RS-485 ports in a PC? |
| You may add a multiport board, which had RS-422 or RS-485 ports, in your PC. |
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| What's multiport board? |
| Multiport board is an interface board for the purpose of increasing the number of serial communication port, I.e. RS-232, RS-422 or RS-485 compliant communication ports, for your PC. |
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| What's the characteristics and transmission distance of RS-232 interface? |
According to the specification of EIA-232 standard, the transmission characteristics are as follows. | Baud Rate (bps) | Distance (Meter) | | 2400 | 60 | | 4800 | 30 | | 9600 | 15 | | 19200 | 7.5 | | 38400 | 3.8 | | 57600 | 1.9 | | 115200 | 0.9 |
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| What's surge protection? |
| Surge protection is realized by a special device for protecting ports from TOV (Transient Over Voltages) which comes from lightning, electrostatic discharges and other forms of high voltage. TOV is always the major factor responsible for damaged components and unreliable data transmission. To improve this problem, we use Transient Voltage Suppresser on our I/O ports to clamp surge voltage to protect ports from TOV. |
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| What's termination resistor? When and how to use it? |
For RS-422/485 serial communications, when an electrical signal travels through two different resistance junctions in a transmission line, the impedance mismatch will sometimes cause signal reflection. Signal reflection causes signal distortion, which in turn will contribute communication errors. The solution to this problem is to establish the same impedance at the line ends as in the line itself by terminating them with resistors.
The value of the termination should equal to the characteristic impedance of the transmission line. The resistors should be added near the receiving side in parallel with positive and negative polarity. |
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