Summary Of Lu Types And Representative Ibm Products - IBM 6400 Setup Manual

Appendix D
Physical and Logical Unit Types
PU type 2.1
The PU type 2.1 is the physical unit type that is required for an LU 6.2 (see LU
type description following). Examples of PU type 2.1 is an IBM 3820, IBM
3935, or PSF/2.
Summary of LU Types and Representative IBM
Products
Listed below are the LU types that SNA currently defines and the kind of
configuration or application that each type represents. Also mentioned are
hardware or software products that typically use each type of logical unit. A
logical unit (LU) describes the type of relationship that the Host VTAM and
applications have with a specific device such as a printer. This relationship
determines the commands supported from the host to the device and the type
of feedback the device gives to the host.
LU type 0
LU type 0 printers are Non-SNA Local or Bisync connections. This mode is
also commonly called DSC (Data Stream Compatibility) mode printing. An
example of an LU 0 printer connection is an IBM 3816 attached to a non-SNA
3174 control unit. Not all printers support this type connection. This
connection type is used when VTAM is controlling the non-SNA control unit
and device.
LU type 1
An LU type 1 is for an application program that communicates with single or
multiple-device data processing workstations in an interactive, batch data
transfer, or distributed data processing environment. The data stream
conforms to the SNA Character String (SCS) or Document Content
Architecture (DCA). Examples of printers that are able to communicate via
LU1 are 4230, 4234, 3930, 6400 and others.
LU type 1 is the basic logical unit type for SCS, IPDS, and AFPDS (PSF)
printing. The type of connection is determined by the application that will be
driving the printer. The selection is made by changes in the VTAM logmode
entry that is used for the logical unit. See the examples for the type of
connection desired.
LU type 2
LU type 2 is use by an application program that communicates with a single
display workstation in an interactive environment, using the SNA 3270 data
stream. Type 2 LU's also use the SNA 3270 data stream for file transfer. An
example of an LU type 2 device is a 3270 display such as a 3278, 3178, and
others.
284