This is the first ML1400 (1766-L32BWA) we have used. I understand it has 32 embedded I/O. (20 in/12 out) . I understand the outputs, O:0.0, O:0.1, O:0.2, etc. With the inputs since I have 20, what do I do after I:0.15? I thought 15 was the highest you could go. What do I call the last 4 inputs?
Thanks in advance!
Full Version: ML 1400 I/O addressing
QUOTE (brinkmann @ Oct 27 2009, 04:34 PM) 
This is the first ML1400 (1766-L32BWA) we have used. I understand it has 32 embedded I/O. (20 in/12 out) . I understand the outputs, O:0.0, O:0.1, O:0.2, etc. With the inputs since I have 20, what do I do after I:0.15? I thought 15 was the highest you could go. What do I call the last 4 inputs?
Thanks in advance!
Thanks in advance!
How its displayed depends on how you configure the display properties.
If the I/O Bit Display Mode is:
Slot/Bit then I:0/0 to I:0/19 will be the input addresses
Slot.Word/Bit then I.0.0/0 to I.0.1/3 will be the input addresses.
Edited per b_carlton's corrected post.
Actually the first 16 can be addressed as I:0/0 - I:0/15 or in the more proper way I:0.0/0 - I:0.0/15
The last 4 can also be addressed in two ways: I:0/16 - I:0/19 or as I:0.1/0 - I:0.1/3
Either are valid. One emphasizes the bit count from the start of the area. The other emphasizes the word and the bit within the word.
You can set RSLogix 500 to display these address references either way. With a project open and a ladder selected go to View - Properties. Choose the Address Display tab. Ffor I/O bits you can choose to have them displayed in the Slot/Bit (First Method) or Slot.Word/Bit (Second Method) [Edit - as Mickey has so quickly shown]
The last 4 can also be addressed in two ways: I:0/16 - I:0/19 or as I:0.1/0 - I:0.1/3
Either are valid. One emphasizes the bit count from the start of the area. The other emphasizes the word and the bit within the word.
You can set RSLogix 500 to display these address references either way. With a project open and a ladder selected go to View - Properties. Choose the Address Display tab. Ffor I/O bits you can choose to have them displayed in the Slot/Bit (First Method) or Slot.Word/Bit (Second Method) [Edit - as Mickey has so quickly shown]
I understand the display modes. I didn't know if I:0/16 thru I:0/19 were valid addresses. Thanks to both!
You have already received the answer that you were looking for, however, I would like to add that these are not really addresses, but they are predeclared variables or tagnames or pointers that point to the acutal memory locations used in the controller. All AB PLC's, excluding Automation Controllers control and compact logix, predefine all of the variables for you. Although it is conventional to refer to these as addresses, it is good to keep in mind that they are pointers and move around in actual memory locations depending upon the expansion and contraction of your data files. The convention of I:0.0/00, O:0.0/00, B3:0/0 etc only exist on your laptop and not in the controller. It is not neccesary to know this to write code for a PLC, but it is nice to know.
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