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Lead Contents

Thumbwheel Switches

With Thumb Rotary Switches, a character dial is turned to switch an actuator and set a value. They are also called digital switches. OMRON provides many models with different sizes and operation methods.

Overview Features
Principles Classifications
Engineering Data Further Information

Related Contents

Primary Contents

Explanation of Common Terms

Output Codes

Binary CodeCombined 2-value ("0" and "1," "OFF" and "ON," etc.) sign.
Decimal CodeUses the ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
Binary Coded Decimal CodeEach decimal number is represented by a binary code (see following table).
Binary Coded Hexadecimal CodeEach hexadecimal numeral is represented by a binary code. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E,
and F represent the sixteen possible values.

+/- Dial Display ("-PM" Models)

It is possible to produce 06-type models (binary coded decimal code) that display "+, −, +...−" instead of "1, 2, 3...9".
The model numbers used for this type of Switch are A7[]-206-PM and A7[]-206-PM-1. Below is an example of the A7BS-206-PM. The Switch's output terminal 1 and common terminal are used for binary output.

Thumbwheel Switch

Thumbwheel Switch_Fig

Example of A7BS-206-PM

ModelSwitch Unit or ConnectorCommon terminal numberTerminals connected to common
A7BSSwitch UnitC1248
Dial+ (0)
- (1)
+ (2)
- (3)
+ (4)
- (5)
+ (6)
- (7)
+ (8)
- (9)


1.The solid dot ● indicates that the internal switch is ON.

2.Numbers enclosed in parentheses are the dial displays for the A7BS-206.

Attaching Stoppers

Stoppers are mechanisms for preventing the wheels rotating outside set ranges. There are internal stoppers that are set at setup and external stoppers that can be set as required at any time. For example, a wheel that normally displays any number in the range 0 to 9 can be restricted to the range 0 to 5 using a stopper.

Add -S[][] to the suffix, specifying the range in the blanks.
Example: A7PS-203-S05

Units to which stoppers can be attached are the A7DP, A7D, A7BS, A7BL, A7PS, A7PH, and A7AS. Consult your OMRON representative for details on individual model numbers.

On the outside of the A7BS-[]-S is a Stopper Pin with which the user can make any setting.

The A7CN-2, A7CN-1, A7CN-L2, A7MD, and A7MA cannot be equipped with stoppers.

Built-in Diodes

"-D" Models (Cathode Common)

Cathode Common_Fig

Applicable Models:

"-D" Models (Anode Common)

(Special specification)

Anode Common_Fig

Applicable Models:

Note:The A7MD has special specifications (anode common). Be sure to connect the terminals with the correct polarity.

The configuration for the A7MD-106-P-D is shown below.

Configuration for the A7MD-106-P-D_Fig

Note:The diode (DAP202K, made by Rohm) is installed inside the case.