Local card reader
IMS supports a local card reader (for example, 2540 or 2502) as an input device. Before operation, however, you must enter a /START LINE command from the master terminal to activate the card reader.
You can then place the card deck in the hopper and make the reader ready. The reader remains active and able to read cards until you enter a /STOP LINE command or until an I/O error occurs.
If you press the end-of-file button, IMS enqueues the last message read for processing regardless of whether it was terminated by a slash-period (/.) delimiter. IMS then issues a read command to allow you to add another deck of cards when needed. If you do not press the end-of-file button, IMS does not enqueue the last message for processing unless it is a single-card input or IMS reads a slash-period. This allows you to fill the hopper with a partial tray of cards without determining whether the last card is also the end of the IMS message. In this case also, a read is left outstanding so you can continue with the input deck by filling the hopper and making the reader ready.
Communicating with IMS
IMS delineates a segment by the presence of an end-of-media (EM) character (X'19', card punch 11-1-8-9) in any column of the input card. IMS ignores any text following the EM character. If no EM character occurs, IMS assumes a segment to be 80 characters in length. The character string slash-period (/.) immediately preceding the EM character (if present) or as the first two characters in the following input card terminates a message. This allows you to input variable-length data, even though BSAM is reading fixed-length records.
When you assign a SYSIN data stream to a local reader line, IMS reads the entire file of data and closes the device. You can restart the line using a /START command after IMS notifies you that it has processed the file.
Responding to errors
If an I/O error occurs, follow standard I/O error-recovery procedures for the device. If IMS detects invalid data, it stops the line. Correct the condition, reenter the deck beginning with the transaction that caused the failure, and restart the line from the master terminal. You should use the /SET command to identify the input destination in order to prevent data errors in the middle of input streams.