- Software
- IQANdesign
-
Questions
Using MD5 as sole master module for machine functions
With the recent obsolescence of the MD4 modules, will the MD5 modules be able to be used as the sole master module and control machine functions in conjunction with expansion modules?
What are the risks of using the MD5 with expansion modules (XC43, LC5, XC23, etc.) to control machine functions without additional master modules?
I know another post implied that the main concern with not using the MD5 to control machine functions was the slower cycle time, but it appears that issue has somewhat been fixed with the lower minimum cycle time now listed at 20ms for the MD5. Is that no longer or less of a concern now?
We have had many bad experiences with multi-master systems, so I would like to avoid going back to an MC43 module, if at all possible. We've been using the MD4 modules with XC43 modules to control machine functions with very good success with a cycle time of 50ms, so the cycle time would not be an issue for us unless there are other limitations of the MD5 that make it unreliable for machine function control.
IQANdesign lets me use the MD5 as a direct replacement for the MD4 modules without any warnings about not using it in conjunction with expansion modules to control machine functions.
Customer support service by UserEcho
It all about functional safety requirements...if you are required to use functional safety modules - then you will require at least one MC4XFS to run the code on then it can be a master to other XC43's etc. The MD5 is not a functional safety module.
Thank you for the insight!
Is this also the case with the MD4 modules? I don't see them listed as "FS" capable, so maybe we've been operating without functional safety functionality this whole time. (We haven't had issues and our machines typically don't require this level of safety certification or operate in an unsafe manner.)
MD4 is not a functional safety controller either. XC4x expansion is functional safety, but only FS when connected to a master that supports FS, such as MC4xFS. The logic inside the MC4xFS needs to be functional safety and constructed in a way that meets requirements.
MD4 with XC4x is not possible for functional safety.
MC4xFS with XC4x is possible for functional safety, provided the logic in constructed safe and additional requirements are met with installing components external to the module.
Find the installation manual for MC4xFS modules, it lists requirements for the additional FS inside red boxes, worth a read as it explains it very well.
I appreciate the information.
If the only concern is meeting functional safety requirements, then it seems weird that they're making it a big deal that the MD5 is intended only as a display module and should be used in conjunction with an MC4x module for machine functions, when they didn't do that with the MD4 modules.
The MD4 instruction book explicitly shows it as the primary controller:
Whereas the MD5 instruction book explicitly states it's recommended to be used only as the display in a multi-master system:
If the concern is truly only about meeting EU functional safety standards, it should be stated clearly that the MD5 can be used as the primary controller in applications that don't require functional safety.
The MD5 series feels like a step backwards in functionality. I thought the "M" stood for Master module, when it seems like these should be treated more like expansion modules. But actually worse, since it will also come with all the downsides of multi-master systems and the requirements for matching project checksums to avoid system mismatch errors. And the inconsistent firmware update times when updating multi-master systems can be extremely frustrating. The single master system with expansion modules just makes field replacements and updates SO MUCH easier.
I suppose it is probably best practice to use the MC4x for machine function control code and we'll have to bite the bullet and move to multi-master systems with the MD5s, but it is disappointing and will be painful.