Remote Human Interface - Trane CVRC-M-1D Manual

Remote Human Interface

General Characteristics
Each unit control can support two human interfaces, one machine
mounted ("local") and one remote. A remote human interface is not
weatherproof, and is intended for indoor use. The remote human
interface is mounted in a plastic enclosure. It uses a molded rubber
keypad, not a membrane keypad. The keys will have the same labels on
both the local and remote keypad.
IPC Buffer
The use of a remote human interface requires that an additional module
be added to the unit control. The IPC Buffer Module is added, to buffer
and protect the inter processor communication bus. This is required
because the bus is brought outside the unit. The buffered IPC link will be
electrically identical to the COM4 non-isolated protected digital
communications link. With the correct twisted pair type, the remote
display can be 5000 feet from the unit.
Multiple Unit Communication
The machine mounted human interface communicates only with its
associated unit. The standard remote human interface communicates
with one unit. The remote human interface has an option that enables it
to communicate with up to four units. An extra circuit board is added to
provide the three additional communication channels. A separate wire
pair is run from each unit control to the remote human interface.
Configuration
The remote human interface uses the same circuit board and software as
the machine mounted human interface. Each circuit board must be
configured as either local or remote by the placement of a shorting block
on pins labeled 5 on the circuit board. When 5 pins 1 and 2 are
connected together, the human interface acts as the local human
interface. When 5 pins 1 and 2 are not connected together, the human
interface acts as a remote human interface.
The remote human interface will detect the presence of the multiple unit
option board by using the internal loop back nature of the RS485
transceiver chip. On power up, after the self test is complete, and after
the human interface identifies itself as remote, the human interface sends
a character on the unit four communication line and looks for a response.
Any response indicate the option board is present, since the character
may be overwriting a message on the line and result in a modified
character or a communication error indication.
Operation
The operation of the remote human interface will be identical to the
operation of the machine mounted human interface, with the following
exceptions.
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