Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 463)

Section 8
Communication Interface
8-30
The 9/260 and 9/290 CNCs have a DH+ (Data Highway Plus)
communications module available that provide DH+ communications.
With this module, the 9/Series can communicate to pass/receive data over
DH+ with other Allen--Bradley DH+ compatible devices.
A wide range of services are supported that allow you access to PAL and
part program variables, part program management, CNC status, etc...
Details on the DH+ communications module are provided in a separate
9/Series Data Highway Plus Communication Module Users Manual
(Catalog number 8520-DHM). Refer to this publication for further details.
END OF SECTION
8.11
DH+ Communications