RS485 TO ETH ( B)
7 . 2 . STORAGE MODBUS GATEWAY
This product can save the content of the read register inside the gateway, so that the speed
of Modbus TCP query can be greatly improved, and the performance is even better when it
supports multi- host access.
Figure 26 Working Mode of Storage Modbus Gateway
As shown in Figure 26: The general Modbus TCP data flow direction is (1) (2) (3) (4). That is,
the Modbus TCP command is first converted into the corresponding command of Modbus RTU,
and then the device responds to the Modbus RTU command to the Modbus gateway, and then
the Modbus gateway is converted to Modbus TCP again and sent to the monitoring host
computer.
We know that Modbus TCP is network communication, and the transmission speed is very
fast. Generally, it can respond within 3ms, while Modbus RTU is RS485, which generally has a
speed of 9600bps. It usually takes at least 30ms to send and return a command. The query
response time of such ordinary non-storage Modbus gateways is relatively long. In addition, if
there are a lot of host computers at the same time to query data at the same time, then the
serial port will be congested. If the network is like an expressway, and the serial port is like a
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