gtps2m39 | ACF/SNA Data Communications Reference |
The response for logical units sending messages to TPF depends upon the LU device type. Input messages received from logical units attached to 3601, 3602, 3274 or 3276 cluster controllers must request exception response (-RSP, that is, negative response only). Otherwise, the data returned in response to a properly sent request serves as request confirmation. Messages received in error from LUs attached to 3274 or 3276 controllers result in TPF sending a Clear/Start Data Traffic (SDT) SNA command sequence. TPF also informs the operator that an error has occurred.
Input messages received from logical units attached to a 3271 control unit request "no response." When an error is detected, TPF discards the input message and sends a CLEAR command. The terminal operator must press the RESET key, which is located on the keyboard, and reenter the message.