Chengdu Ebyte Electronic Technology Co., Ltd.
NB144 User Manual
Copyright ©2012
，
Chengdu Ebyte Electronic Technology Co., Ltd.
31
needs.
As an optimization of multi-host request performance, the storage gateway can only work in the TCP server
mode, which improves the response speed of the network side.
Features:
（
1
）
gateway has a 2K cache for storing instructions and returning results (reading 10 holding registers as
an example, it can store about 67 instructions and returning results);
（
2
）
RTU response timeout automatically clears the cache to ensure the real-time and authenticity of the
data;
（
3
）
The polling interval can be customized, 0 -65535 ms ( default: 200ms) ;
（
4
）
The gateway will poll the RTU device according to the storage time of the command used for
configuration. If the MODBUS host does not query the command again during the storage time, the
gateway will automatically delete the storage command to release the cache;
（
5
）
The first instruction and control instruction ( 05 , 06 , 0F , 10 function code) will directly access the
RTU device;
（
6
）
Only support 0 1 , 0 2 , 0 3 , 0 4M od bus function code query result storage;
5.4.4 Configurable Gateway
The gateway automatically polls the RTU device registers according to the pre-configured MODBUS
commands (only supports the configuration of MODBUS read commands), and the commands in the non-storage
table will directly operate the RTU device, and the frequently read commands can be stored in the gateway in
advance, which can shorten the Response time (command to query configuration), the data will not be sent directly
to the server and will only be returned after the request of the Modbus host, which is similar to the use method of
"simple protocol conversion". If you need to automatically upload the data to the server, please select "automatic
upload". Due to the above characteristics, the serial port side of the configurable gateway can only be connected to
the Modbus slave station.
