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.
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What Everybody Ought to Know about PLC Numbering Systems
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
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.
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 register table. (%SR) Like the %S registers, this contains additional information when programming or monitoring the controller.
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
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