Shanghai ZLAN Information Technology Co., Ltd Tel: +86-17321037177 http://www.zlmcu.com
57
Note that when the serial device server is used as the TCP client, it does not have the
storage function and will automatically switch to the non-storage type.
The features of the storage Modbus are listed below:
1) The first Modbus TCP query command is non-storage. It is necessary to wait for the
RTU device to return the data at a slow speed before replying the register content to
the Ethernet port.
2) If a specific instruction no longer has the query form upper computer on the network
end in 5 seconds, it will automatically delete this instruction and no longer send it
from the serial port to the RTU device.
3) At present, the Modbus cache of 10K can be stored. For ordinary single register
query, about 500 instructions are stored at the same time.
4) When there are multiple instructions queried at the same time, send in accordance
with the order, send first instruction
first instruction reply
wait for 485
anti-collision time (refer to Multi-host part)
send the next instruction... . Go back to
the first instruction after the last instruction finished reply.
7.3 Disable Storage Function
Although the storage Modbus has a fast response speed, some users do not wish that
RTU devices to receive a large number of query instructions of affecting the internal
processing speed of the instrument. You can turn off the storage function at this point.
The way to disable storage is to click on the "More Advanced Setting" button in the
“Device Setting” dialog box, removing the Support and the Enable as shown in figure 47
and click ok. Go back to the device setting and click Modify Setting.