Envision Peripherals NV3128 - Manual (Page 52)

NV3128 RS-422A Machine Control Data Routing Switch 3-4
On older systems, DIP switches on the Command Interpreter establish
the logical ID for each of the two levels and also configure the partition
parameters. On newer systems with the Universal Control module,
levels and partitions are set up using UniDiag.
3.1.1 POINT-TO-POINT CONNECTION RULES:
1. If Requested Destination is in use as a source:
Find all destinations, break connections and tristate (turn off) the ports.
2. If Requested Destination is already tied to Source
Find all the Destination ports to which that Source port is tied. Break
all connections between that Source and its Destinations. Tristate
Source Port and all its Destinations.
3. If requested Source is in use as a Destination
Find all Sources tied to that port . Break those connections and tristate
the Source ports.
4. Configure Source and Destination ports and make the forward and reverse
crosspoint connections.
3.1.2 MULTIDROP CONNECTION RULES
A connection in which a single source connects multiple destinations is always
addressed on Level II. The first destination connected is the controlled device
with answer-back capability. The received signals at all subsequent port
connections are not routed.
1. If requested Source is currently driving other Destinations:
tristate the response line of the requested Destination port.
2. If Requested Destination is in use as a source:
Find all destinations, break connections and tristate (turn off) the ports.
3. If requested Source is in use as a Destination
Find all Sources tied to that port . Break those connections and tristate
the Source ports.