Westermo RM-115S - Manual (Page 10)

115S Serial I/O Module User Manual
Page 10 June 2011
1.1.6 Communications
The 115S modules have two communication ports: RS232 and RS485. The RS485 port
communicates using E-Series protocol. Both ports support Modbus protocol.
The RS232 port is intended for configuration. The RS485 port is intended for normal
operation and can be used in a multi-drop setup.
There are two address switches on the base of the module. When the switches are set
within the range 01-99, the module uses Modbus protocol on the RS485 port, with the
Modbus address defined by the switches. Setting both address switches to 00 configures
the module to use E-Series protocol on the RS485 port. Whenever these address switches
are changed the unit should be reset by disconnecting power.
Note - When configured for E-Series protocol the maximum number of expansion
modules per radio is 10 as each module requires 3 addresses.
When using E-Series protocol, the port settings are fixed at 9600 baud, 8 data bits, no
parity, 1 stop bit.
The Modbus communications settings are configurable as follows:
Modbus type: RTU, ASCII with 8 data bits, ASCII with 7 data bits. (Note that the
configuration software only supports Modbus RTU. A Modbus Master can select ASCII
protocol by writing to the appropriate register. See Appendix A.)
Baud rate: 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 76800, 115200
Parity: none, odd, even
Stop bits: 1 or 2.
The modules are fitted with a termination switch for the RS485. Set this switch only on
the last module in a multi-drop RS485 configuration.
The ELPRO E-Series software is used to configure the 115S modules as part of an
E_Series network. The hardware set-up for items such as expected pulse rates and analog
signals is also available through this software.
When used as a Modbus-only device, stand-alone configuration software
(cfg_115S_Vx.xx.exe) is available to set up the modules. All required software may be
downloaded from the ELPRO website.