Steam flow measurement data (flow, pressure, temperature) is transmitted to the DCS via RS485
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The steam flow measurement data (flow rate, pressure, temperature) is transmitted to the DCS via RS485 over a distance of 500 meters; what type of cable should be used?
For RS485 communication over distances of up to 500 meters, it is recommended to use shielded twisted-pair cables, such as CAT5 or CAT6. This type of cable can effectively resist electromagnetic interference, ensuring the stability and reliability of data transmission. .
RS485 twisted shielded communication cable
The amount of data transmitted in this case is not large, so conventional twisted pair cables are sufficient; a transfer rate of a few dozen kbps is enough
When using MODBUS communication, the data for three points amounts to 6 bytes. With MODBUS function code 16, the instrument can transmit the data of multiple holding registers at once; for DCS, function code 03 is used to read the data of multiple holding registers simultaneously. The amount of data is only a dozen bytes or so; at a rate of 9600, 900 bytes can be transmitted per second, which is more than sufficient. If the signal quality is poor, it can be reduced to 1200 BPS, which will still work just fine. Regular twisted pair is fine. If it gets better, add a shielding layer and use Siemens PROFIBUS cables. It’s extremely expensive.
485 signal transmitted to DCS over a distance of 500 meters – what cable should be used?
Wireless transmission module, with a transmission range of 3000 meters; it works very well, and the cost is just a few hundred yuan per pair.