Our PC10420, PCI20, PCI20U and PCX20 ARCNET interface adapters work under QNX 4.x. The driver to use is "net.arc20". This driver is included with QNX 4.x and information about using it is available at:
www.qnx.com/developers/docs/qnx_4.25_docx/qnx4/utils/n/netarc20.html
A special ARCNET driver was written to support certain Corman ARCNET cards under QNX 2.x, but these cards are no longer supported by Corman.
To date, no ARCNET driver has been written for versions of QNX later than 4.x.