Expansion I/O Memory Map; Adding Expansion I/O To Configuration Software - Elpro Technologies 915U-2 User Manual

Page 54
The default serial parameters of the RS485 port are 9600, N, 8, 1 which match the
defaults of the 115S serial expansion modules. The parameters can be changed, to
increase poll speeds in larger systems however the serial modules will need to match
that of the 915U-2 RS485 port.
Also if more than 3 serial expansion modules are added the "Maximum Connections" for
the RS485 port on the "Serial" page will need to be adjusted.
Note: Reducing the "Maximum connections" will slightly improve the
serial scan time however make sure the slave addresses falls within the
"Maximum connections". If the Slave address is above the "Maximum
connections", it will not be polled.
Next, connect the serial expansion module and take note of the module address (Rotary
switches on the bottom) as this address will be used as an offset to locate the I/O within
the 915U-2.
Also make sure the last module in the RS485 loop has the termination switch on
(down).
Failure to terminate the RS485 correctly will result in the modules not
operating correctly.
115S Expansion I/O Memory Map
I/O data on the 115S module is read into memory locations according to their Modbus
address. The maximum number of Modbus addresses is 24.
Each 115S module has an "Offset" which applies to the location of all of its registers.
This Offset is equal to the units Modbus address multiplied by 20.
If the modules Modbus address is 15, the Offset value will be 15 X 20 = 300.
E.g. If connecting a 115S-11 (16 x DIO) with address #15
• Digital input 1 will be at register location 10301.
• Digital Output 1 will be at register location 301
If using a 115S-12 (8 x DIO & 8 AIN) with address 16
• Digital input 1 will be at register location 10321
• Analog input 1 will be at register location 30321
See Appendix C: "Expansion I/O Store Registers". For a more detailed address map of
the serial expansion I/O modules.

Adding Expansion I/O to Configuration Software

Select the sub branch "Expansion" under the I/O/ Branch of the module in the
configuration software.
Select "Add" to enter new I/O modules.
Page 54
915U-2 Wireless I/O
User Manual