36 • SMP Gateway User Manual
Interface Description
Constraint for the SMP 4-20 and the SMP 8-40:
An SMP 4-20/SMP 8-40 CPU board can support up to 4 different bit
rates for the serial ports located on the front panel. This means that if
you specify that the console serial port is configured for RAS, only 3
other bit rates will be available for the remaining 4 serial ports on Board
A and that if all the other Board A serial ports are used, 2 of the 5 serial
ports must have the same bit rate. Note that if you set the console serial
port to Reserved and you do, in fact, accept incoming direct serial
connections on the console serial port as well as on the 4 remaining
serial ports, the SMP Gateway application will disable the console port
connection. This constraint obviously does not apply to Board B, since it
has 4 serial ports and there are 4 bit rates available.
Redundancy
Use this value to indicate that the serial port is reserved for connecting
2 SMP Gateways together as a redundancy group. See “Grouping 2
SMP Gateways for Redundancy”, page 183.
ELO Touchscreen
Use this value to indicate that the touch input information of an Elo
touch screen will be transmitted to the SMP Gateway using a serial
cable, through this serial port.
Radio
Use this value to indicate that a radio will be connected to this serial
port.
Reserved
Use this value to indicate that the serial port is reserved for purposes
other than those stated previously.
5.5.2 Configuring the Operation of the Serial Ports
Each serial port needs to be configured with the appropriate settings for the connected device.
In the left pane, open the Connections branch to display all the supported connection types.
Click Asynchronous Serial Ports to display the list of available ports.
Note that if you choose “Redundancy” as the interface for a serial port, this port will not
appear in the list of Asynchronous Serial Ports, as it will be reserved for connecting the
2 SMP Gateways that will be grouped together.
In the right pane, enter the settings for the selected serial ports.
The required settings are usually provided in the device manufacturer’s reference manual:
If you are using RS-485 2-wire communication, choose RS-485. If you are using RS-485
4-wire communication, choose RS-422.
Choose the device communications settings: baud rate, byte size, parity and number of
stop bits, such as 9600 baud, 8 bits, no parity, and 1 stop bit.
Choose the device hardware handshaking mode:
If the link type is RS-232, most devices do not use handshaking, so you should keep
the default values: RTS to Always On, DTR to Always On, and CTS to Ignore.
If the link type is RS-422, set RTS to Always On. You shouldn’t have any problem
if you keep the other default values: DTR to Always On, and CTS to Ignore.
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