epca assert errors are are caused when critical System IRQ/Memory resources of the Server, which are currently being used by the Digi product, are "stepped on" by some other device on the Server.
epca assert errors can typically be avoided by protecting the resources which your Digi product uses, within the Server's own System BIOS software. We have no specific guidance to provide on how resources can be reserved within your particular System BIOS, due to each different type/version of BIOS may handle that in a different way.
For further information on memory resource contention issues when using Digi Serial Card products, please refer to the following articles:
How do I resolve resource contention issues when installing ISA or EISA cards?
Resolving Hardware Contention, IRQ or Memory Conflict with PCI Adapters
Will Digi PCI serial card adapters share an IRQ with other PCI devices?
Windows 2000 Does Not Detect my Digi adapter On Boot up.