Horner XL4 Numbering System and Addressing

We will now look at the Horner XL4 numbering system and addressing. Data is stored in different memory-type locations called registers. The registers can be either bits or words (16bit). Multiple registers can be used together to store a 32-bit value. (Double word) This all in one controller has several additional registers to handle some of the HMI communication. Let’s look at all of the areas in the controller.

Previously we discussed the following in our Horner XL4 Series:
System Hardware
Installing the Software Cscape
Cscape Software Setup
Establishing Communication

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Numbering System Notation – Horner XL4

Cscape uses the conventional method of addressing similar to other controllers.
% – required character
[type] – register type – R, I, Q, etc. see below
[offset] – this is the address of the register
Example: %R33
Note: You can also use [offset][type] for the format. So 33R is the same as %R33.

The following table will show the Register addressing types found in the Horner XL4 controller.

Register Name Bits Description Memory Retentive Address Size
%AI Analog Input 16 Local Analog Input No  512
%AQ Analog Output 16 Local Analog Output No  512
%AIG Global Analog Input 16 Analog Input that come from the network. No  32 per ID
%AQG Global Analog Output 16 Analog Output that is sent to the network No 32 per ID
%D Display Bit 1 Digital output flags that will display the corresponding screen No 1023
%I Digital Input 1 Local Input bit No  2048
%IG Global Digital Input 1 Network Input bit No 64 per ID
%K Key Bit 1 Local Input bit from the front panel of the controller No  5
%M Retentive Bit 1 Retentive single bit Yes  16000
%Q Digital Output 1 Local Output bit No  2048
%QG Global Digital Output 1 Network Output bit No 64 per ID
%R General Purpose Register 16 Retentive registers Yes  49999
%S System Bit 1 Single bit predefined for system use No  13
%SR System Register 16 Register predefined for system use No  192
%T Temporary Bit 1 Retentive single bit No  16000

Address size will show the numbers that you can use to define the bit or register.
Example: %M1 to %M16000 – The Cscape software will notify you of an address that has been entered incorrectly.

Registry Map for Local I/O – Horner XL4

Each model of the Horner XL4 OCS will have a registry map for the local inputs and outputs. The following table is from the Horner manual showing the addresses of the local I/O.
Horner XL4 Numbering System and Addressing
Cscape will automatically assign the next available register if you enter a type and  ‘?’. Example: I?  will appear as %I0001. Enter I? again will appear as %I0002.
Note: You do not have to enter the ‘%’ every time you enter an address. Cscape will enter one for you.

System Bit Addressing – Horner XL4

The following is the system bit table. (%S) It contains useful information when programming the controller.
Horner XL4 Numbering System and Addressing

The following is the system register table. (%SR) Like the %S registers, this contains additional information when programming or monitoring the controller.
Horner XL4 Numbering System and Addressing
Horner XL4 Numbering System and Addressing
XL4 SR Registers
Additional information can be obtained by the on-line help in Cscape.

All of the documentation can be downloaded at the following URL:

Next time we will look at the user interface.

Watch on YouTube: Horner XL4 Numbering System and Addressing

If you have any questions or need further information please contact me.
Thank you,

If you’re like most of my readers, you’re committed to learning about technology. Numbering systems used in PLC’s are not difficult to learn and understand. We will walk through the numbering systems used in PLCs. This includes Bits, Decimal, Hexadecimal, ASCII and Floating Point.

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