Modbus Slave Mode of Modbus Gateway USR-M511
2020-05-11
Modbus Slave mode means serial port device connected to M511（Modbus Gateway, Modbus RTU to TCP） is Modbus Slave.
1. M511 work in Modbus Slave mode allow at most 32 Modbus Slaves connect through RS485/RS422 to achieve RS485/RS422 multiple Masters Polling function. But speed of RS485/RS422 interface will be a little slow because of the limitation of RS485/RS422 baud rate.
2. M511 work in Modbus Slave mode support 16 Masters querying Slave information.
3. M511 work in Modbus Slave will default open Memory Function to solve the problem that Modbus Masters in network side query Modbus Slaves too slow. When open this function, M511 will a utomatically update the stored data from serial port Modbus Slaves and reply stored data to network side Modbus Masters directly.
4. Modbus work in Modbus Slave mode can apply to four applications: One Master to one Slave; one Master to multiple Slaves; m ultiple Masters to one Slave; multiple Masters to multiple Slaves.
Application diagram as follows:
One Master to one Slave
User can change Modbus Slave mode parameters by web server as follow:
A.Work mode: Four types work modes.
B.Enable Modbus Over TCP/IP: Open this function, M511 will work in transparent transmission and don’t proceed protocol conversion. If network side protocol is Modbus RTU/ASCII, this function must be used. If network side protocol is Modbus TCP, this function can’t be opened.
C.Enable Memory Function:When open this function, M511 will automatically update the stored data from serial port Modbus Slaves and reply stored data to network side Modbus Masters directly.
D.Local Port Number: Default is 502 and don't need change.
E.Timeout Reconnection: No data transmission over this time, M511 will automatically disconnect and reconnect remote Slave.
F.Modbus Timeout: Modbus response time which must be accordant with serial port Modbus Master.
