HPDEVCONTROL

Syntax

                I32     CA    I32      I32
  HPDEVCONTROL (status, ldev, itemnum, item);

Parameters

status

32-bit integer (required)

Returns the status of the HPDEVCONTROL call. If no errors or warnings are encountered, status returns 32-bits of zero. If errors or warnings are encountered, status is interpreted as two 16-bit fields:

Bits (0:16) comprise status.info. A negative value indicates an error condition, and a positive value indicates a warning condition. Refer to the MPE/iX Error Message Manual Volumes 1, 2 and 3 for a description of its value.

Bits (16:16) comprise status.subsys. The value represents the subsystem that sets the status information. There is no specific subsystem identifier for HPDEVCONTROL.

ldev

character array (required)

Passes the LDEV number of the device to be accessed. This parameter is a 200-character packed array.

NOTE: This parameter must be delimited with a printable, non-numeric character and must be zero left-filled: "00000007" or a00000007a Whatever delimiter begins the parameter must also end the parameter. The delimiter itself must not appear within the parameter. a0000a007a will cause an error because a appears within the parameter. The LDEV parameter must be defined as 200 characters in the calling program. However, because logical device numbers are currently limited in size to 10 bytes only the leftmost 10 bytes of the array is used. For this reason, the ldev should be loaded into the leftmost 10 bytes of the 200-character array before the call is made.

It also may be important to understand that the system converts this parameter to a pointer before passing it to the intrinsic. It should not be coded as a pointer in the calling program, however.

itemnum

32-bit integer (required)

Specifies which operation is to be performed.

item

32-bit integer (required)

Itemnum/ Mnemonic	Item Description
100/I32	Load Media: Attempts to load the media (tape devices only).
101/I32	Online: Programmatically places the peripheral online (tape devices only).

NOTE: A call with an item number 100 (load) to a device which is already loaded is acceptable (produces no harmful result). However a tape device would go offline (only an HPIB DAT drive would not go offline). It is recommended that this intrinsic be called with item 100 followed by 101 whenever it is used for a tape device.

Related Information