scott.lawrence said:
it's a 1769 L35E controller...
As I'm sure you are aware, that is a CompactLogix controller and so is the 1769-L24ER. The Module Discovery option does not support the 1769 CompactLogix modules as they cannot be added online. They must be added to the project offline and then downloaded.
Only 1756, 1715, and 5069 modules can be added online...
492329 - How to use Module Discovery Feature
Access Level: TechConnect
(I know you cannot read that technote. I've posted it for the benefit of those who can.)
However, not supporting certain modules should not result in the error message you are receiving. The Module Discovery applet should open and show unsupported modules but with a specific message which prevents them from being created in the I/O Configuration.
I've just gone online to a running CompactLogix 1769-L32E and the Module Discovery applet opened as expected.
CompactLogix incompatibility aside...
The 1756-L63 controller at firmware revision 20.xx should work as Module Discovery was introduced at v20 software and the 1756 modules do support online addition. Also, the issue mentioned in the first technote I posted should not apply to the L63 as it does not have an embedded Ethernet port. That technotes instructs you to go online via the controller's embedded Ethernet port instance instead of the controller instance on the backplane. Both allow you to go online but only the embedded instance will work for Module Discovery. Also, just so you are aware, that first technote also shows a screenshot of the same error you are receiving.
There is something in general preventing it from opening for different versions of software and different platforms. Possibly a common component at fault, but which?
G.