CHANNEL INTERFACE MODULE (CIM)

SECTION 8 CHANNEL INTERFACE MODULE (CIM)
8.1 DESCRIPTION

Refer to 3000 Series Switch Service Information manual, Part No. 001-3139-102, for the component layout, parts list and schematic. Refer to Figure 7-1for the Basic Board block diagram. The Channel Interface Module (CIM) connects the Switch to the Multi- Net and LTR Repeaters. Each repeater has a CIM that monitors and controls the repeater through logic signaling.

8.1.1 REPEATER SIGNALING

The CIM uses one of three methods to exchange control information with its repeater: RS-232 lines, Audio Frequency Shift Keying (AFSK) data on a separate audio path, or by AFSK data in a blank and burst mode on the voice audio path.

8.1.2 REPEATER CONTROL

The CIM controls the repeater with restart, enable and disable, executes requests to read and write to the repeater's memory, and tells the repeater transmit code, hang or send turnoff. The CIM receives confirmation of all requests made to the repeater and sends information the repeater receives.

8.1.3 VOICE CONNECTION

The CIM provides a 4-Wire 600 ohm balanced voice connection to the repeater, converts audio to and from Pulse Code Modulation (PCM), transmits and receives on the PCM buses, and controls voice audio gating to and from the repeater.

8.1.4 INTERNAL COMMUNICATION

The CIM uses the Intra-Terminal Data Bus (IDB) to communicate to other modules and send messages to and receive messages from the Call Processor that controls its actions.

The status of the CIM/Repeater combination is determined by the other modules by what the CIM transmits on the Channel Status Bus (CSB). The other modules monitor the CSB and determine if a CIM has the appropriate group and status for the type of communication the module requires.

8.2 CIM SETUP PROCEDURE

8.2.1 SWITCH SETTINGS

Refer to Figure 8-1for Alignment Points Diagram.

Command and Control Communication

The command and control communication to the Multi-Net Logic Module or the Repeater Interface Module may take place by several different forms.

The form chosen is typically dependent upon the location of the repeaters to the CIM equipment.

1.If the location is within 200 feet, it is suggested that the communication take place digitally on the secondary line.

2.If the location is greater than 200 feet, the commu- nication taking place uses the Audio Frequency Shift Keyed (AFSK) modems. This may take place on the Secondary lines if the appropriate facilities are available; i.e. 4-Wire leased line or microwave link.

3.The AFSK may be done using the blank and burst mode on the Main audio lines. This is typically used when the link is by leased lines or microwave, but the number of lines available does not allow for the use of the secondary line connections. (This has a low level burst of data (100 ms) at the end of trans- missions.)

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