Unit installation

7-1

Chapter 7: Serial Port Commands

This chapter deals with the the following topics:

Information about serial transfers

RS-232 baud rates

Other serial port options

Sending serial messages out of the main serial port

Sending serial messages out of the radio cards' serial ports

Where the Serial Ports Are:

The RLC-3 has a serial port on the motherboard, next to the power jack, that is used for entering

commands on the controller. This is called the main serial port. The top DB-9 connector on each

radio card is also a serial port and is usually used for controlling a remote base.

Controlling what Serial Messages are Sent:

This section only refers to the main serial port, since it is the one you use for entering commands

and that the controller uses to tell you when there is an error. When the controller is reset (such as

when the power is turned on), it sends a serial message that tells you the controller type, software

version, etc. Of course you will only see this message if you have a computer or serial terminal

connected to the main serial port. If you then type a command on the computer or serial terminal

and press enter, the controller will process the command and print on the screen either what it did

(except for a few commands that don't print anything) or an error message telling you what went

wrong.

If you enter a command from a radio using DTMF, the controller normally will not print anything

on the serial screen. It "suppresses" that serial so if you are programming from the serial port at the

same time someone is entering DTMF commands, the responses to their commands won't confuse

you. You can keep the responses to commands entered by DTMF from being suppressed by

turning serial suppression off with command 060. This can be handy for figuring out what is going

wrong when entering DTMF commands.

Commands 162 and 169 bypass the check to see if serial is suppressed so they always print. Since

you will normally want serial suppression to be turned on, these commands are useful for sending

messages that you always want to be printed, even if the command to send them is entered from a

radio port or executed by the scheduler or some other internal device.

The RS-232 Serial Protocol:

Most serial devices (computers, mice, external modems, serial terminals, etc.) use the RS-232 serial

protocol. The main serial port on the RLC-3 is RS-232 compatible. The serial ports on the radio

cards can be made to be RS-232 compatible by installing a Dallas DS1275 chip into the socket

labeled U8 (underneath the tone level pot). Make sure that there are no jumber blocks on header

J5 (right next to U8) when you plug in the DS1275, or you could destroy the chip.