RS485 TO ETH ( B)
Figure 28 Multi-host function demonstration
As shown in Figure 28, in the normal mode, when two hosts: host A and host B are
connected to the serial server at the same time, host A sends (1) command, RS485 device
receives (2) command, RS485 device returns (3) ) Command, but the serial port server will send
(4) to host A and (5) to host B at the same time. Since the host B did not send the query, but it
also received the response command (5), the host B may generate a communication abnormal
error. In the multi-host mode, there will only be instructions (4) but not instructions (5), because
the serial server will automatically remember the host that needs to be returned, and only return
the instructions to the most recent communication host, and the query of host A will only reply
to A, host B queries and replies to host B.
Another function is that in the normal mode, when the host A and the host B send data at
the same time, the combination of instructions will be generated on the RS485 bus, so that it
cannot be recognized normally; in the multi-host mode, the serial server can schedule A and B to
use the bus. Prioritize the conflict problem of simultaneous access by multiple machines in an
effective way.
When the conversion protocol is "None", the multi-host function is not enabled by default.
When you need to enable multiple hosts, please click "More Advanced Settings" in the device
configuration dialog box, and then check "RS485 multi-host support".
7 . 5 . MULTI - HOST PARAMETERS
The meanings of "Enable RS485 Multi- Host " and "Enable RS485 bus conflict detection" are
introduced as follows.
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