The 'solving' of similar issues in the market is just as astounding, but people who have used it are not as simple as they say. In the actual application process, there are always such problems. The ports are inactive and the communication process is interrupted. The technical personnel of Nyco company have been practicing for many years and have accumulated practical experience in many aspects.
One solution: Use a pair of NC-RS485 to solve We all know that RS485 protocol interface level is low and this protocol supports 1.2KM transmission, the serial communication usually only uses RX, TX, GND three lines, Therefore, in this case, as long as two converters are connected back to back, the requirements can be met. At the same time with two converters between the two lines of transmission, to facilitate the realization.
The schematic diagram is as follows:
Figure 1
Evaluation Advantages: This solution is only applicable to the RS232 terminal using only TX, RX, GND three-wire communication; NC-RS485 is a passive conversion device, the converter uses two-wire transmission to facilitate on-site connection; lower cost.
Disadvantages: NC-RS485 equipment is a passive device, so RS232 and RS485 end no opto-isolation safety is relatively poor in this solution, if you need to isolate to choose active isolation equipment; transmission distance is limited by 1.2KM; only far Pass RX, TX, GND three lines.
The second solution is to use the NC-RS232R long-line driver.
If the transmission distance is farther or the transmitted signal is not only TX, RX, GND three lines, but also RTS, CTS, DTR, DSR and other handshaking signals, the above solution can no longer meet the requirements. In this case, the long-line driver is more cost-effective. One of the programs.
The schematic diagram is as follows:
Figure II
Evaluation Advantages: This program has a long transmission distance; cost-effective.
Disadvantages: Therefore long drive RS232 port to steal power from the RTU side, so this program has a higher level of remote RSTU port RTU, non-standard RTU COM port can not make NC-RS232R work
The third solution is through the NC-MODEM277 fiber MODEM.
In special industries such as electric power, water power, and petrochemicals, the on-site environment is harsh, and electromagnetic interference is severe. At the same time, the stability of data communication is relatively high. At this point, the above two schemes can no longer meet the requirements. Optical fibers are usually used as the transmission medium.
The gesture is as follows:
Figure 3
Evaluation Advantages: high transmission reliability; small and stable equipment; the highest rate of 1152K, according to the requirements of optional single, multi-mode optical fiber; equipment, flexible, according to the requirements of optional RS485/422 mode.
Disadvantages: Dedicated transmission medium is required, and the cost is high.