Changing Logic within a running AOI on ControlLogix

The Siemens implementation online FB programming in step 7 is quite terrifying. The thing it lets you do are so wrong and dangerous is it breathtaking. Just stick in a few more OBs to stop the processor from catching on fire and you are golden.

TIA is much more cautious about maintaining instance storage integrity but at least it tries to stop you from doing something stupid.

Geoff White said:

The Siemens implementation online FB programming in step 7 is quite terrifying. The thing it lets you do are so wrong and dangerous is it breathtaking. Just stick in a few more OBs to stop the processor from catching on fire and you are golden.

TIA is much more cautious about maintaining instance storage integrity but at least it tries to stop you from doing something stupid.

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I would say that the things that lets you do is what makes it better than others. At the end of the day, if you don't know the platform you're working on, either you shouldn't be working on it or the system shouldn't be live when you do it.

My comment was related to how the concept of function has been around for a long time with Siemens PLC's but in others like Rockwell it has never been implemented as such until recently. Yes, you can now pass inputs to subroutines, but it's clunky at best.

#1 for Siemens, although even from the S5 days how embarrassing when the red light starts to flash. I like the way you can virtually download nearly all the blocks without putting it in stop, but can be a bit dangerous. I remember sending some updated blocks via email to a customer, however one of the data blocks had null data in it, and should contain in one of the words an indirect address for recipe selection, this was checked in the initial start OB and if out of range it would put it to "1" corresponding to recipe 1, as he downloaded the blocks on-line then the OB would not be processed so red light