X25AM Configuration and Management Manual

Attribute Descriptions
X25AM Configuration and Management Manual—523424-004
5-20
Default Values for the CUD
Default Values for the CUD
The default values for the CUD are configured by the X25AM I/O process modifiers
CALLUSERDATA and NOCALLUSERDATA. CALLUSERDATA is the default
specification.
If CALLUSERDATA is configured for the I/O process, the default for the CUD field is 4
zero bytes (0000) for both PTP and ITI protocol devices.
If NOCALLUSERDATA is configured, the default for PTP subdevices is no CUD field
and the default for ITI subdevices is a CUD field with 4 zero bytes (0000).
Dynamic and Static Values
The CUD value is static if you set it using the SCF ADD SU or ALTER SU command to
the X25AM subsystem. The CUD value is dynamic if you set it programmatically using
the SETPARAM 41 or SETMODE 28 procedure.
The static CUD value is the value present in the CUD field when a subdevice is first
opened, before the application issues a SETPARAM 41 or the SU receives an
incoming packet.
The dynamic CUD contains the values that may have been specified during a session
with a SETPARAM 41 procedure or that have been updated by the receipt of an
incoming packet with a CUD field. The dynamic CUD is the last CUD received or sent
in a call request packet or set by SETPARAM 41.
You can display the CUD value by using the INFO SU command with the DETAIL
option. If the static CUD values have not been overridden by a dynamic value, the SCF
INFO, DETAIL command displays the static CUD values. However, any incoming CUD
value overrides the CUD you set through SCF. The incoming value is the value that
you then see displayed.
The values of the dynamic CUD remain until the SU is closed and are not reset when a
call is cleared. If you want to reset the values of the CUD before the call is cleared, you
can use SETMODE 28 to reset the CUD to the static CUD.
For more information about setting the CUD programmatically, see the X25AM
Programming Manual.
Examples of the CUD Attribute
The following example adds the SU $X25P1.#TERM, gives it the protocol ITI, and sets
the CUD to a value of 123456789a:
-> ADD SU $x25p1.#TERM, PROTOCOL ITI, DEVTYPE (6,0),&
-> RECSIZE 80, CUD “123456789a”
The following example alters the value of the CUD for the SU $X25P1.#TERM:
-> ALTER SU $x25p1.#TERM, CUD “200”