User manual

Page 58 915U-2 Wireless I/O
Page 58 User Manual
4.2.9 Serial Configuration
The 915U-2 has an RS-232, and an RS-485 port for serial communications. These ports
may be used to connect external Modbus RTU devices via the Modbus TCP to RTU
Gateway and or ELPRO serial expansion I/O modules.
Select the Operating Mode and the normal serial parameters, Baud Rate, Format, Flow
Control, etc from the drop down lists.
Modbus TCP to RTU Gateway
The Modbus TCP to RTU Gateway allows an
Ethernet Modbus/TCP Client (Master) to
communicate with a serial Modbus RTU Slave.
The 915U-2 makes this possible by internally
performing the necessary protocol conversion.
The conversion is always performed by the
915U-2, which is directly connected to the
Modbus serial device (i.e. only this module
needs to have Modbus TCP to RTU Gateway
enabled).
Figure 34 - Modbus TCP/RTU
Request Pause – Enter the delay between serial requests in milliseconds
Response Wait – Enter the serial response timeout in milliseconds – a serial retry will
be sent if a response is not received within this timeout.
Connection Timeout – Enter the TCP connection timeout in seconds – if no
Modbus/TCP data is received within this timeout then the TCP connection will be
dropped. Set this field to zero for no timeout.
Maximum Tries – Enter the maximum number of request retries performed serially.
Expansion I/O
By default the RS485 port will be automatically enabled for “Expansion I/O “.
This means that when expanding the I/O all that is needed is to add the ELPRO
Expansion I/O module/s, e.g. 115S-11, 115S-12, or 115S-13 to the RS485 port and the
I/O will automatically be available from within the 915U-2‟s I/O store. See User Manual
for location addresses.
By default the Data Rate, Data Format will all be standard 9600, N81 and none for Flow
Control which matches the default Serial baud rate and data Format of the 115S serial
expansion module.