I/O 875
INPUT/OUTPUT DEVICE
USER REFERENCE SHEET
FOR
THUMBWHEEL SELECTOR SWITCH ASSEMBLY
Part No. 46S02875-XXXX
For use with MicroTrac DSD Local or Remote Input/Output boards
FRONT VIEW OF ASSEMBLY
THUMBWHEEL
SWITCH
BANK
DECIMAL LOCATER
PRINTED
CIRCUIT
BOARD
JUMPER
REAR VIEW OF
PRINTED CIRCUIT BOARD
BANK SELECT
J2
8 7 6 5 4 3 2 1 0
J1B
J1A
TB1
Effective 5/30/90
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INTRODUCTION
The Thumbwheel Selector Switch
Assembly may be interfaced to any of the
Local or Remote I/O boards that support
thumbwheel inputs. The Thumbwheel
Selector Switch Assembly comes in many
configurations, such as number of digits,
decimal point location, and whether or not a
sign selector is present.
HARDWARE DESCRIPTION
CONFIGURATION
One bank of thumbwheel switches is
mounted to a printed circuit board to form
this assembly. The Thumbwheel Selector
Switch Assembly comes in many
configurations; up to 6 digits, or 4 or 5 digits
and a +/- sign selector, may be included in
the switch bank mounted on this printed
circuit board. In addition, a decimal point
location spacer may be mounted. The
assembly is designed for mounting in a
panel cutout, held in place by tension clips
on the ends of the switch bank.
POWER REQUIREMENTS
The Thumbwheel Selector Switch
Assembly receives input power (+24VDC and
COMMON) via the Thumbwheel Switch
Interface (ribbon cable connection) from the
Local or Remote I/O board to which it is
interconnected, either directly or as part of a
daisy chain.
INPUT/OUTPUT BOARD INTERCONNECT
There are two 26 pin connectors (J1A and J1-B) on the assembly's printed
circuit board that are to be connected to a
Local or Remote I/O board, or to other
Thumbwheel Selector Switch Assemblies,
through use of 26 conductor ribbon cables.
The cable is intended to be connected in a
daisy chain style from Thumbwheel Selector
Switch Assembly to Thumbwheel Selector
Switch Assembly, originating from the Local
or Remote I/O board.
NOTE
When used as a Local I/O device for
a MicroTrac DSD drive, the ribbon
cable conection to the Local I/O
board can be made directly, without
the need of a Terminal Transition
Adapter PCB.
PUSH TO LOAD
In addition, a PUSH TO LOAD input
may be connected to this printed circuit
board. When the PUSH TO LOAD input is
connected to COMMON (either through a
push button or directly tied), then the input
is asserted. A connection terminal for the
PUSH TO LOAD input and a connection
terminal that supplies COMMON are
provided TB1 on the printed circuit board.
PUSH TO LOAD affects all thumbwheel
switches connected (i.e. daisy chained) to
this printed circuit board.
INSTALLATION AND HOOKUP
This assembly is factory installed and
should require no further connections to be
made to it. However, if it should become
necessary to install the assembly in the
field, then the following steps should be
taken:
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WARNING
HAZARDOUS VOLTAGES CAPABLE OF
SEVERE INJURY OR DEATH MAY BE
PRESENT WITHIN CABINET. BEFORE
OPENING CABINET DOOR, DISCONNECT
AND LOCK-OUT INCOMING POWER.
CAUTION
TO AVOID DAMAGE TO ELECTRONIC
COMPONENTS, DO NOT MAKE ANY
CONNECTIONS WITH POWER APPLIED.
USE PROPER ELECTROSTATIC
DISCHARGE (ESD) PROCEDURES WHEN
HANDLING PRINTED CIRCUIT BOARDS.
A. In long cable runs, take care to
prevent excessive voltage drop.
B. Separate the leads used for speed
reference, feedback, and other low level
signals from those used for the motor
armature, field and AC power. Do not run
these two groups in the same conduit or
wire trough.
C. Provide shielded and twisted leads as
indicated on the schematic and
Interconnection Diagrams. Connect all
shields on shielded wire to system common
(not ground) on one end only. Use Twisted
shielded pair wire for long runs.
1. Turn off incoming power.
2. Locate where this assembly is to be
physically mounted. Refer to the System
Schematic for the location.
3. If replacing an existing assembly, then
disconnect all cables and wires to the
assembly from their connectors. Then
unmount the existing assembly.
4. Mount the assembly into its proper
position. Note that the printed circuit board
will fit through a cutout properly sized for
the switch bank.
5. Connect all of the cables and wires
per the Interconnection Diagram.
SETUP
CAUTION
TO AVOID DAMAGE TO ELECTRONIC
COMPONENTS, DO NOT MAKE ANY
CONNECTIONS WITH POWER APPLIED.
There are nine possible Thumbwheel
Switch Banks for connection to a Local I/O
board. The Thumbwheel Switch Bank is
selected by the BANK SELECT jumper on
connector J2 on the Thumbwheel Selector
Switch Assembly's printed circuit board.
Thumbwheel Switch Bank 0 through 8 may
be selected. To determine the proper BANK
SELECT jumper position, refer to the
System Schematic.
IMPORTANT
Refer to the equipment Interconnection
Diagram for detailed wiring information.
Ensure that wire size and disconnect
devices conform to the installation
contractor’s drawings and to all applicable
codes. Observe the following:
Ensure that there is no duplication of
Switch Bank numbers in a daisy chained
group of Thumbwheel Selector Switch
Assemblies.
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