Envision Peripherals NV3128 User Manual download pdf (Page 69)

NV3128 RS-422A Machine-Control Data Routing Switch 4-7

4.2.4 I/O ASSEMBLY: EM0040-XX

The I/O module is a bidirectional interface between the router's

crosspoint matrix and the external machines. Two modules, each

supporting 64 ports, make up the full complement of I/O circuits. The

assembly plugs simultaneously into both backplanes, communicating

with the crosspoint module through the Signal Backplane and with the

external machines through the I/O Backplane.

A total of 64 proprietary receiver/driver submodules pass data to and

from the I/O backplane. Each submodule makes the D connector it

services function as either a controlled or a controlling device, depending

on whether it is addressed as a Source or as a Destination.

Two 64x64 crosspoint ICs use control information received from the

Command Interpreter to gate the submodule transmitters and receivers

on or off appropriate to the directions of data flow through the port.

The command information is resistor-coupled from the Signal Backplane

into line buffer/driver circuits and their associated resistor networks. A

similar circuit arrangement receives crosspoint data from the Signal

Backplane and applies it to the port submodules for transmission to

external machines.

Receive data from the port submodules is driven over the Signal

Backplane to the Crosspoint Module by drivers ICs.

Submodules each operate separately on the raw DC input voltage to

provide +5VDC operating levels for 1/2 the available circuits. By thus

dividing the circuitry, the impact block of a failure is correspondingly

reduced.

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Envision Peripherals NV3128 User Manual Page 69