Remote 3270 errors (VTAM®)

A remote 3270 can inform IMS about certain unusual conditions that it detects during its operation. When IMS receives a message of this type, called a sense-status message, from a 3271, 3274, 3275, or 3276, IMS determines if it indicates an error or some normal condition. If the message indicates an error, IMS formats the message for printing and sends it to the z/OS® system console.

The sense-status messages, in general, indicate the following 3270 conditions:

• Device end (for example, operation complete on printer)
• Intervention required (for example, out of paper or 3270 display power off)
• Busy (operator action with unprotected screen)
• Hardware-detected errors (for example, data check or control check)

An intervention-required condition can be caused when:

• A display station is turned off (not on 3275)
• A printer is turned off or has its covers open
• A printer is without paper
• A security keylock is in the off position

When IMS detects an intervention-required condition, it suspends output to the unit. When you make the unit ready (by turning power on or by putting paper in the printer, for example), IMS resumes output. If a message is in progress when IMS detects the intervention-required condition, IMS resends that message from the beginning. For a 3270 printer, IMS can only detect an intervention-required condition that is caused by a power-off condition when IMS attempts to select that device for printing.

To determine which printers and displays are in an intervention-required state on a remote 3270 line, enter a /DISPLAY LINE PTERM or /DISPLAY NODE command. Those units in an intervention-required state display as COMPINOP (component inoperative).

IMS handles the printer on the 3275 (3284-3) differently when it detects the intervention-required condition. IMS marks the printer as having a component inoperable. However, the 3275 display continues to receive output messages and retains all input capabilities. Operations on the 3284-3 printer resume when you make the printer ready.

IMS retries 3271, 3274, 3275, and 3276 hardware-detected errors several times before it considers the error to be permanent. If you do not correct the error, IMS sets the physical terminal to pstopped and inoperative status and considers it unformatted.

IMS tries to pinpoint the cause of any hardware failures. It tries to eliminate the smallest component possible (for example, a terminal rather than a control unit, or a control unit rather than a line) when a problem forces elimination of resources. For a VTAM-attached 3270 terminal, IMS issues a /CLSDST command to disconnect the terminal. After you make appropriate repairs, you can restore IMS operation by issuing a /START LINE PTERM or /RSTART LINE PTERM command for those terminals that are part of the failing unit.

IMS tries to ensure that a terminal correctly receives all data sent to it. However, certain printer operations, including the Copy function, cause mechanical actions on the printer after the data has been transferred. For some errors occurring under these circumstances, no error recovery is possible, and none is attempted.