Using HDLC/LAP-D Protocol
Status and Error Messages
14TM_TABLE_SIZE Protocol table sizes too small
The configured terminal table size is too small to allow
Unsolicited Status Messages
This section describe the unsolicited status messages which may be received on the ZLU which is set as the receiver for a terminal using this protocol. The status codes received may or may not have bit 7 set. Bit 7 is the down bit (masked by IO_DOWN_MASK). The down bit is used as an indicator of the link status. When an error occurs on the link or the link is enabled after being disabled, the protocol attempts to enter multiple frame acknowledged operation. Until the attempt succeeds or fails, the down bit is clear (i.e. the terminal is considered to be up until proven otherwise). If the attempt subsequently fails, the down bit is set; otherwise the down bit left cleared. The following status messages are generated in response to terminal enable and disable requests:
0 | IO_OK | No error detected |
This status message is generated in response to a terminal enable request after multiple frame acknowledged operation is established. Note that the down bit will always be clear.
41IO_ALRDY_ENBL Terminal already enabled
This status message is generated in response to a terminal enable request when the terminal is already enabled and the protocol is not currently trying to establish multiple frame acknowledged operation. If the protocol is currently trying to establish multiple frame acknowledged operation, this status message will not be sent. Instead, either a ST25ENBL with the down bit set or an IO_OK status message will be sent.
42IO_ALRDY_DSBL Terminal already disabled
This status message is generated in response to a terminal disable request when the terminal is already disabled. The down bit will always be set.
Chapter 3 | 33 |