Alpha Technologies Serial System Controller - Manual (Page 15)

1. System Overview
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018-332-C0-002 Rev. B © 2001 TM
Figure 1-4; RS-232 and Alpha/HMS Bus RS-485 Connectors
1.2.5 Serial Communications Interfaces
The SSC has four serial communications interfaces: the internal RS-485; the external
RS-485; the external RS-232; and the ECM port.
1.2.5.1 Internal RS-485
This interface connects the SSC to each XM2 power supply in the system.
The SSC coordinates all system activity and status through the interface. An
offset modular cable is connected from this interface to an XM2 in the system.
Additional offset modular cables connect each subsequent XM2 in a daisy
chain. A USM2 or USM-TI option installed in each XM2 contains two modular
connectors to support this setup. XM2 units can be connected in any order.
1.2.5.2 External RS-485
This interface connects the SSC to an external monitoring device such as an
RF transponder. This interface supports two data protocols; the SCTE HMS022
Power-Supply-to-Transponders Interface and the System Communications
Interface (SCI). The SCTE HMS022 open standard supports basic power
supply and generator status. The SCI is an Alpha proprietary “extension” to
HMS022 and supports product-specific status, configuration, and control
features beyond the scope of the SCTE standard. Consult the specific status
monitoring vendor for products compliant with SSC interface standards.
1.2.5.3 External RS-232
Identical to the RS-485 HMS Bus port, this interface responds to the HMS022
protocol (and extensions). It supports local access to status and diagnostics,
through a PC running Alpha’s Power System Monitor (PSM) application
software. (Contact Alpha Technologies for pricing and availability of the PSM
application software.)
1.2 Indicators & Connections, continued