Mocomtech operation manual CDM-Qx/QxL Modem Connections, EIA-485 Connections CRS-300 to Modems

CRS-300 1:10 Redundancy Switch	Revision 16
Cables and Connections	MN/CRS300.IOM

4.6CDM-Qx/QxL Modem Connections

If adding a modem to an operating 1:N system, care needs to be taken to not interfere with the existing traffic. The cabling, power-up sequence and COMs connections must be correct to avoid contention in the system from the modem Tx carrier. This information is detailed in Chapter 7.4.5 (CONFIG) ACTIVE MODEMS.

As shown in Figure 4-18through Figure 4-21, the CA/WR12069-1 Control Y-Cable provides fault information from the modem and IF-Mute to the modem, and is therefore always required.

4.6.1RMI/TMI Limitations and Considerations

Because the CDM-Qx/QxL redundant modem can only support one type of data interface, the TMIs cannot be mixed within the same CRS-300 Redundancy Switch.

Depending on the traffic data type, the appropriate jumper settings are provided on the TMI to ensure proper operation for EIA-422 with RTS/CTS, DTR/DSR signal using the CRS-316 TMI, or for HSSI with CA/TA signals using the CRS-336 TMI.

IMPORTANT Refer to Chapter 4. MODEM, TMI, AND SWITCH CONFIGURATION for this important configuration information.

4.6.2EIA-485 Connections – CRS-300 to Modems

An EIA-485 Multi-drop cable provides the communication path between the Switch and the modems. There are two types of EIA-485 Multi-drop cable available: a standard CA/WR11417-1 shielded cable to guard against EMC (Electromagnetic Compatibility) concerns, and an optional CA/RB11423-1 ribbon cable. Both are available from Comtech EF Data.

Refer to Figure 4-16to connect the EIA-485 multi-drop cable between the Switch and the modems as follows:

•Connect and secure (1) CA/WR11418-1 EIA-485 terminator on each far-end DB-9F connector of the appropriate EIA-485 multi-drop cable (the standard CA/WR11417-1 shielded cable or the optional CA/RB11423-1 ribbon cable).

•Connect and secure one end of the Null Modem Cable CA/WR11419-1 to the DB-9F connector labeled “485 Pass-Through” on the CRS-300’s CRS-230 System Controller.

•Connect and secure the EIA-485 multi-drop cable to all CDM-Qx/QxL modems and to the DB-9M connector on the Null Modem Cable.

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