a Quick RS Logix question 1

[xJAyx]

I'm editing a program written by my predecessor and I have a quick question.
I have to modify a LES statement.
The Source A is an input and the Source B is a constant. There are 4 parameters on the right hand side of the instruction box, one lists the input, and the other 3 are 4 digit numbers. I can edit the input (directly across from 'Source A) and the second number (directly across from 'Source B'), however I can not edit the other 2 numbers.
From what I can tell the fourth number is the one I need to edit, but it is not editable. It seems to possibly be a variable entered somewhere else, but I can't find it.
Thanks in advance for your help.

 

[djs]

Hello;
Is this program in relay logic (ie contacts and coils), function block programming (ie boxes) or statement text? Also what type and version of RsLogix are you using? (5, 500 or 5000)

 

[ADMIRALKEN]

the LES block appears to have four numbers, but in fact there are only two. Should/could look like this

Source A: I:7.0
32767

Source B: 320
320

The numbers under the sources are the values of the source.
In this example Source A has a current value of 32767, source B (a constant) has a value of 320.
If you need to change the valve of the "fourth" value, then just change the third one.

 

[xJAyx]

Thanks for the help. The program is in RS Logix 500, for a micrologix 1500 processor.
I am working in the ladder logic which has both relay and boxes if I understand your question correctly.

The issue is that the bottom two numbers are not the same, one is 8400 the other is 6267. If this were a constant they should both be the same. Is 8400 a memory location?

 

[ADMIRALKEN]

sounds like you are working off line, have you viewed this
instruction on line?

or if you verify your program the values will up date

 

[killemall]

Yep, Not an issue.
If you select EDIT->Verify Project, they will be both the same.
The number next to SOURCE B is all that matters. The other number is just the last value.

If you are working online, you can not change constants in micrologix.
Go offline, edit the value next to SOURCE B, verify project, save, then downlod to PLC.
It is a good idea to use a register for your constants, so you can modify them when online. eg. N7:0. Then you can change the fourth value as this would be the register contents.

 

[QUIPPDUDE]

When are AB going to get the message that the lack of On-Line editing for the Micrologix Series 1200 and/or 1500 is a serious drawback.

They have touted the MLX1500 series as a lower cost/more space efficient replacment for the SLC-500, but the software/firmware combination is missing what has been to date one of the most useful AND unique attributes of Rockwell RSLogix, namely "ON-LINE EDITING".

Yes indeed Mr. Rockwell, we are all very impressed with the abilities of ControlLogix and CompactLogix, but this level of sophistication, complexity and added software cost is not needed for a vast number of PLC applications.

Please....please....please give us back our on-line editing capabilities on the MLX family.

 

[killemall]

Having spoken with people at Rockwell on this very subject, it seems they are never going to have online editing ability for micrologix range.

They are more keen to push the CompactLogix range as the slightly more expensive better alternative with online editing ability.

Having used both, I can see their point. The compact logix is a vastly better processor, and not a huge price difference. They have a cheap version of RSLogix5000 available which can only program CompactLogix range.

What they try to hide when giving a price comparison, is the fact that although the processor is only a little more, for the same project, you also need extra a power supply, an input module and an output module. This is to replace the I/O and power supply on the MicroLogix Base.

It is frustrating that the customer just looks at the price, they don't care that I rip my hair out using commissioning a job on MicroLogix.

I guess we will just have to live with it, and stay mad at our friends at Rockwell Automation!