Using HDLC/LAP-D Protocol

Status and Error Messages

64

ST25ENBL†

Link NOT established on ENABLE

 

 

This status message is generated in response to a

 

 

terminal enable request after it is determined that

 

 

multiple frame acknowledged operation can not be

 

 

established. The down bit will always be set.

65

ST25DSBL

Link disconnected on DISABLE

 

 

This status message is generated in response to a

 

 

terminal disable request after multiple frame

 

 

acknowledged operation has terminated. The down bit

 

 

will always be set.

77

ST25ENF

ENABLE failed - bad config

 

 

This status message is generated in response to a

 

 

terminal enable request when the terminal’s

 

 

configuration is invalid. The down bit will always be

 

 

set.

The following status messages are sent after an error occurs when the link is in multiple frame acknowledged operation. The error conditions include cable faults, inability to receive acknowledgment of transmitted frames or receiving frames that are inconsistent with multiple frame acknowledged operation. When one of these error conditions occur, the protocol attempts to reestablish multiple frame acknowledged operation. After the attempt has either succeeded or failed, the unsolicited status message that reflects the original error condition is sent. If the attempt fails, the link is considered disconnected and the down bit will be set in the status; otherwise the link has only been reset and the down bit will be clear.

66

ST25XDCD

Link disc. on loss of carrier

 

 

The card is no longer receiving the required

 

 

communications signals. This can be caused by incorrect

 

 

port configuration or disconnected/faulty cabling.

68

ST25RTRY†

Exceeded retransmit limit

 

 

A frame was transmitted N200 times without receiving

 

 

an acknowledgment from the remote.

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Chapter 3