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Figure 36 multi-host function demo
As shown in figure 36, in normal mode, when two hosts, host A and host B, are
connected to the serial port server at the same time, host A sends (1) instruction,
RS485 device receives (2) instruction, and RS485 device returns (3) instruction,
but the serial port server sends (4) to host A and (5) to host B at the same time.
Since host B did not send a query, but it also received a reply instruction (5), host
B may generate a communication exception error. In the multi-host mode, only
instructions (4) will be given and no instructions (5) will be given, because the
serial port server will automatically remember the host that needs to be returned
and only return the instructions to the nearest communication host. The query of
host A will only reply to A, and the query of host B will reply to host B.
Another effect is that in normal mode, when host A and host B send data at the
same time, the instruction combination will be generated on the RS485 bus, so
that it cannot be recognized normally. In the multi-host mode, the serial port server
can schedule the priority of A and B on the use bus, so as to solve the conflict
problem of simultaneous access of multiple machines in an effective manner.
If the conversion protocol is "none", the default is not to enable multi-host function.
If you need to enable multi-host, please click "more advanced options" in the
device configuration dialog box, and then check "RS485 multi-host support".
7.5 Multi-host Parameter
The meanings of "RS458 multi-host support" and "RS485 bus collision detection
function" are described as follows.
Figure 37 RS485 multi-host support
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