3270 SNA and non-SNA device sense fields

Table 1 and Table 2 provide information on sense fields for a 3270 SNA or non-SNA device. See z/OS Communications Server: SNA Programming for information about programming for the IBM® 3270 Information Display System.

Table 1. SNA sense information received at the application program
SNA sense	SNA definition	Cause for exception
80xxyyyy	Path error	Request could not be delivered ¹
400A0000	No-response not allowed	RESPOND=(NEX,NFME,NRRN)
400B0000	Chaining not supported	CHAIN=(FIRST or MIDDLE or LAST)
20030000	Bracket state error	BRACKET=NBB and no bracket currently exists ²
20010000	Sequence number error	Session sequence number error
10030000	Function not supported	CONTROL=(DATA or CLEAR)
10000020	Request error	Command rejected
08210000	Session parameter not valid	Parameters not valid in BIND
08130000	Bracket bid reject—No RTR Forthcoming	BRACKET=BB and a bracket already exists ²
0000zzzz	Other exception	Device exception—USENSEI values are defined in Table 2
Note: `xx` is defined in SNA Formats. For a PU type 1 3270 terminal, `yyyy` can be set to 0010 (intervention required). For a BSC 3270 terminal attached to a communication controller, `yyyy` represents the NCP system response byte and extended response byte returned for some path error conditions. For information on how these bytes are defined, see NCP and EP Ref. Summary and Data Areas, Volumes I and II. This sense code applies only if bracket protocols are being used in the session.

Table 2. Explanation of USENSEI Information
USENSEI Byte 0									USENSEI Byte 1								Meaning
	0	1	2	3	4	5	6	7	0	1	2	3	4	5	6	7
	.	.	.	.	X	.	.	.	.	.	.	.	.	.	.	.	Device busy
	.	.	.	.	.	X	.	.	.	.	.	.	.	.	.	.	Unit specify
	.	.	.	.	.	.	X	.	.	.	.	.	.	.	.	.	Device end
	.	.	.	.	.	.	.	X	.	.	.	.	.	.	.	.	Transmission check
	.	.	.	.	.	.	.	.	.	.	X	.	.	.	.	.	Command rejected
	.	.	.	.	.	.	.	.	.	.	.	X	.	.	.	.	Intervention required
	.	.	.	.	.	.	.	.	.	.	.	.	X	.	.	.	Equipment check
	.	.	.	.	.	.	.	.	.	.	.	.	.	X	.	.	Data check or bus-out check
	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	X	Operation check
	X	X	X	X	.	.	.	.	X	X	.	.	.	.	.	.	Reserved
Note: Transmission check is indicated for a channel-related error (such as PCI, channel program check, protection check, channel data check, channel control check, interface control check, or chaining check) for a channel-attached non-SNA 3270.

The application program can disobey the LU Type 0 protocols by attempting to send:

If you attempt any of the preceding items, the following results occur, depending upon the actual type of terminal used in the session: