EM3270 Manual

Data-Stream Switching Method
1-12 110332—Tandem EM3270 Manual
Product Components and Operation
Data-Stream Switching Method
In a dual-application session, the terminal user can switch from the Tandem application
to the IBM application and from the IBM application to the Tandem application by
pressing the SWITCH key. Alternatively, you can install a procedure that inspects a data
stream to detect switching commands that automatically switch applications. This data-
stream switching method is described in Appendix G.
Hunt Group Feature
The EM3270 emulator includes a hunt group option that can be used to open
consecutively numbered TR3271, SNAX/XF, or SNAX/CDF subdevices until a
subdevice that is not busy is found or until the end of the group is reached. Each group
of subdevices might correspond to a particular IBM host application. This feature is
handy when several terminal users are sharing one or more groups of subdevices. The
users do not have to search for a free subdevice since the EM3270 emulator does it
automatically when this feature is enabled.
You define a hunt group by naming the TR3271, SNAX/XF, or SNAX/CDF subdevices.
The last one or two characters in each subdevice name within a group must be
consecutively numbered. For example, consider the following TR3271 subdevices:
$TR1.#IMS01
$TR1.#IMS02
$TR1.#IMS03
$TR1.#IMS04
$TR1.#IMS06
$TR1.#IMS07
$TR1.#IMS08
When the hunt option is enabled and an emulator session with subdevice #IMS01 is
requested, the EM3270 emulator attempts to open subdevices #IMS01 through #IMS04
in numerical order. A session is established with the first subdevice available. If all four
are busy, the EM3270 emulator will encounter NonStop Kernel file-system error 14
when it attempts to open nonexistent subdevice #IMS05. File-system error 12 is then
reported, indicating that all subdevices in the group are unavailable.
Hunt groups consisting of from 2 to 100 subdevices can be constructed for TR3271,
SNAX/XF, or SNAX/CDF lines. The hunt group option is enabled with the SET HUNT
ON command, and it can be used with sessions that you initiated using the SET HOST,
ADD, and START commands or that the terminal user initiated with the RUN command.
Supported 3270 Features and Devices
Tandem terminals in use with the EM3270 emulator support all IBM 3270 features
consistent with the physical characteristics of Tandem terminals and software emulation
capabilities. The information in this section does not apply to IBM 3270 or Fujitsu 66xx
terminals working with the EM3270 emulator. Appendix A, “EM3270 Emulation
Description,” contains a table of keys and features that are not supported by Tandem
terminals and gives detailed information about the emulation provided. Appendix A also
lists the emulated IBM devices.