HP UX 11i v1 I/O Cards manual Terminal State

NOTE

ZCOM Message Handling

Terminal State

Terminal State

Within the ZCOM subsystem, the terminal state may be either enabled or disabled, activated or deactivated. For normal I/O operations, a terminal ZLU must be both enabled and activated. If a terminal is disabled (regardless of whether it is activated), then no messages can be sent to it or received from it.

If a terminal is enabled but deactivated, then messages can be sent to the terminal, but none can be received. The following table illustrates the different combinations.

Terminal State	SEND	RECV
Enabled/Activated	Yes	Yes
Enabled/Deactivated	Yes	No
Disabled/Activated	No	No
Disabled/Deactivated	No	No

A terminal state of disabled overrides the activated/deactivated status.

For some protocols (such as the NCR 301 protocol), the protocol handler automatically deactivates the terminal when a valid message is received and until it has been processed. Each time a message is received, the terminal must be reactivated by the receiving program, using the zcntl command with the ‘activate’ request code (request code 9, ZCOM_MRQCODE_ACT).

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