How To Troubleshoot Wiegand Reader Problems - Inverted Wiring

By Brian Rhodes, Published Jul 16, 2019, 10:17am EDT

Wiegand is the dominant method of connecting access readers, but problems can arise for installers.

In fact, one of the most difficult reader installation issues to troubleshoot is caused by wiring it wrong.

However, inside we explain how to find the wiring issue using an app, making it possible to diagnose over the phone.

Strange Card Numbers Common Problem

Often, access installers will report issues such as 'All but one of the card readers installed report the correct card number. Cards work on all but that one reader!'

A significantly confusing aspect is the cards function as expected elsewhere. The reader works as expected otherwise except for reporting strange credential numbers, seemingly unrelated to the actual number every time they are used.

Here's an example of this type of issue, captured on a social media group:

The problem often results in dispatching a technician to the site, and can lead to the (ultimately unneeded) replacement of readers and/or credentials, costing hundreds of dollars.

Below we explain how to troubleshoot the issue using Windows Calculator over the phone.

Card **** ***** ** *******

*** **** ****** *******, only ***** *********** *** used ** ******** ***********. Even *** ******** **.** MHz ***********, ***** *** only ******* ** **** on *** **** **** to ********* ***** ** called * '**** ****** number', ** ***.

**** *** ** ***** the **** ****** *******, embossed, ** ****** ** the ****. ** *******, every ****, *** ************* user, **** *** * 'unique' ******.

*** ***** ***** ***** example *** ******** ** credentials:

Problem **** *****: ******** ****** ******

*** ************ ********** ******* reader *** **** ********** must ** ***** ********* for *******, ******** ********** data ** ** ****** between *******.

*** *** ******** ** access *******, **** ********** uses *** ********* *****: generally *** '*****' *** 'white' ****** *****, ******** called *** '******* *****'. Some ********** *** ** observed ** ***** *******, but **** *** ***** readers ************ *** ***** conductors *** ******* ***********.

*** ***** ***** ***** connect ** ****** *** crucial ** ****. ** general, ******* ***** *** connected ** *** '**' and '**' *****, *** the **** *****/******** **** be ********.

**** **********, **** *********** ones, ********** ***** *** 'D0/Green' **** ** *** 'D1' **** *** ** on, ******* * *** problem **** ** **** to ****** ** * casual ****:

Diagnosing ******* ***** ******* **********

****** **** ************ *** wiring ********, *** ******* for ******** **** ****** wiring ******* *** ** done **** * ******* PC ** **** ********/**** the ***** **** **** the ********** ******* ********** by *** ****** *** the ****** ********** ****** on *** **** ******.

*** **** **** ******* is *************** *** **** 'free' ******* **********, ******** any *********** **** ******** decimal ******* ** ****** can ** ****.

*** ***** ***** ***** Windows **********:

  1. ** * **, *********** ********** ** '**********' Mode
  2. **** ** *** ******/*** credential ***** (******* '*****')
  3. ***** *** ****** (***) value (******* '**** **** 0101 ****')
  4. ***** *** ******* ****** value ** **** ****** back **** **********. ******* all '*' **** '*' and **** *****. (******* '0101 **** **** ****')
  5. ***** *** ******* (***) value ** *** ** it ******* *** ******* credential ***** **** ******* on *** ****. (******* '23713')

** *** ******* ***** in **** * ******* the ****/ **** ****** be **** ** *** reader, *** ** *** D1 ***** *** ******** or *********** **********.

*** ******* ** ******* fixed ** ******** *** wires ** ** ** the ******* *****, ******** the **********, ********, ** termination ****** *** ******** Wiegand ******.

Video ***********

*** ***** ***** ************ the *******, ** ** use ******* ********** ** Binary **** ** ***** inverse ****** ** *** system ******* **** ***** values ****** ******** ****:

Wiegand **** ******

*** ******* ***** ****** on *******, ***** ****** binary, ** ******** ********** information ** ****** ***********.

** *******, ******* *********** use *** ***** ** communicate **** ******. **** dormant, **** ** *** two *****, ** (*****) and ** (*****) **** a **** ******* ** 5 *** ** *** line.

**** **** ** **** by *** ****** **** a ********** ** ****, the **** ******* *********** drops ** * ***. This **** ** ********** as ****** * '*' or '*' ****** ***** based ** ***** **** the **** ** ****:

****** ******* ** *********** values, ***** ******* *** either '*' ** '*' and *** *** ******* or *********.

******* ***** ****** *** basic ******, ********** ******** up *** ***** ********** registers **** ** *** wrong ****, ***** ******* a *********** *****, *** access ****** ******* ******.

Does *** **** *** ****

** ****, *** ****** above **** *** **** for *************** **** ********* readers, **** *******.

*****~**% ** *********** ****** they *** ******* *** majority ** *** ****, *** ******* *** encrypted ****** ** **** means **** ******, *********** binary ** ** ****** used.

*************, *** **** ******* uses ****** ** **** one ** *** **** troubling ******** *****, ********** to '*** ** *** middle' ******** ***$** ****** ** ************** **** **** **** details ** ********** ******* often *******$** ** ****.

Comments (5)

Undisclosed #1

07/16/19 02:58pm

Some more calculator fun.

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Brian Rhodes

IPVMU Certified | In reply to Undisclosed #1 | 07/16/19 03:14pm

Hey thanks!  That's cool.  

Basically that document explains how individual card values can be extracted from hexadecimal values using Windows Calculator. This is useful if you need to 'dissect' the records in raw user database or some other manual task.

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Undisclosed #1

In reply to Brian Rhodes | 08/12/19 01:23am

Some more general nerdiness and geekwit across multiple platforms. Did not know where to plug this one since it is not the typical security industry topic however there are other connections to be made with security and hardware. Connect the dots within the box.

https://pagedout.institute/download/PagedOut_001_beta1.pdf

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Undisclosed Manufacturer #2

07/18/19 02:12pm

No need to mess about with hex or binary here, nor getting the number and swapping 0s and 1s.
Simpler to subtract the number from 65535
65535-41822=23713
65535-65523=12

Obviously that doesn't explain why it is wrong, and why this fixes it.

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Undisclosed Integrator #3

07/19/19 01:29pm

Its Complicated to work in HEX, normal installer doesnt have this info

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