Serial Communications Devices

• RF MODEMS Settings

The following INI settings should be used, when communicating via standard RF Modems that do not employ an IP protocol but rather accept serial data input from the computer for direct transmission.  These setting exist (or should be added) to the [MDC] section of the INI file and will be required by both MDC Workstations and the MDC Controller.

[MDC]

COMTYPE=1
SERIAL_PORT=
TX_DELAY=

The COMTYPE setting of 1 is used to indicate to the MDC software that the program should send and receive all data via a serial port and will not use the TCP or UDP protocol.  The SERIAL_PORT setting should be set to the actual serial port number on the computer that is connected to the RF modem.  

Do not confuse the use of standard serial communications with other devices and services that use Windows Dial-up Networking Services (DuNS) to communicate serially to a modem for the purposes of providing an IP network type connection. When such a configuration exists the MDC software should be configured with either a COMTYPE=2 for TCP/IP communications or COMTYPE=3 for UDP communications.

The TX_DELAY setting is used to cause a deliberate delay before sending data to the serial port for transmission.  With some devices a delay can be necessary so that data is not sent too to the RF modem too fast, before it is ready to receive data.

Dedicated RF modem systems can be very fast and reliable and are ideal in situations where commercial data services are limited or unavailable. Likewise, a use of a dedicated RF modem radio system avoids monthly fees to commercial carriers, but does require a substantial investment in equipment and the appropriate FCC licensing.   For use with Crimestar’s MDC system any RF Modem used must be able to support the transmission of binary data.