hpib(7)

Set the timeout. If any transaction for this file takes longer than arg[0] microseconds, it is aborted with a status of ETIMEDOUT returned to the user. This is used mainly for detecting device failure. A timeout of 0 is equivalent to infinity; that is, no transaction will time out.

Set the width of the interface. This request specifies the number of valid data lines on transfers; arg[0] holds the desired interface width in bits. All future read requests inspect only the least significant arg[0] data lines, and all future writes present data on only those lines. The state of all other data lines is indeterminate.

Set the transfer speed of the interface. The desired data transfer speed in kilobytes per second is specified in arg[0]. Note that this value is advisory only, and is typically used by the driver to determine the method of data transfer.

Enable/disable EOI assertion on writes. If arg[0] is nonzero, all subsequent writes end with EOI asserted on the last byte transferred. A zero arg[0] disables EOI assertion.

Make the interface system controller or non-system controller. If arg[0] is nonzero, the interface becomes the system controller. A zero in arg[0] sets the interface to non-system controller. This request is applicable to raw bus files only.

Enable or disable pattern matching on reads. If arg[0] is nonzero, all subsequent reads terminate when the pattern specified in arg[1] is encountered in the input stream. This termination condition is subject to all other termination conditions in effect for the file. Only the n least significant bits of the pattern are used in the match, where n is the interface's current width, set via HPIB_WIDTH. A zero arg[0] disables read pattern matching.

Define signaling events. This request allows the calling process to receive a signal when some event occurs on the HP-IB. The event or events are specified by computing the bitwise inclusive OR of the values from the list below, and placing the mask in arg[0]. All of these events can be enabled on raw bus files, but only ST_SRQ and ST_PPOLL apply to auto-addressed files.

When any subsequent flagged event occurs, the process is sent SIGEMT. The user should set up a handler to trap this signal via signal() or sigvector() (see signal(2) or sigvector(2)). The reason for interrupt can be obtained via the IO_STATUS request HPIB_SIGNAL_MASK. Each request overwrites the previous mask for the file; therefore events can be disabled by using a zero arg[0].

If ST_PPOLL is flagged, the user supplies additional information in the arg array. For raw bus files, the low-order bytes of arg[1] and arg[2] contain eight-bit masks with each bit corresponding to a Data I/O (DIO) line and the least significant bit mapped to DIO1. When a device responds to parallel poll, it asserts the appropriate line; arg[1]'s bits indicate the parallel poll sense of this assertion. Bits set in arg[2] indicate that the corresponding address is capable of responding to polling. For auto-addressed files, arg[1] specifies the parallel poll sense of the assigned device's response to parallel poll. Parallel poll interrupts can be enabled only if the interface is the active controller.

Lock or unlock the HP-IB interface. Setting arg[0] to LOCK_INTERFACE locks the HP-IB interface, giving the calling process exclusive access to the card and bus. The lock is incremental; that is, if the interface is already locked by the current process, additional lock requests increment a per-open lock count maintained in the driver.

An arg[0] of UNLOCK_INTERFACE decrements the per-open lock count; when the total interface lock count drops to zero, the lock is cleared. The lock can also be cleared by setting arg[0] to CLEAR_ALL_LOCKS, which removes all locks held by the current process.

After a successful lock or unlock, arg[1] contains the current lock count for this open, and arg[2] contains the total lock count on this interface.

While the interface is locked, other processes that attempt to access the bus or interface are blocked until either the interface becomes unlocked or the process's per-open timeout (set via HPIB_TIMEOUT) expires. However, if the O_NDELAY file status flag is set (see fcntl(5)), the user request fails and returns immediately with the EACCES error. See the Summary of Privilege Requirements section for a list of user requests that might block.

Set the HP-IB address to which the interface responds when it is not the active controller. The bus address is set via arg[0], and must be between 0 and 30 decimal. Two additional flags, HPIB_TALK_ALWAYS and HPIB_LISTEN_ALWAYS, can be set by computing the bitwise inclusive OR of their values with the address. These flags enable the interface to talk, and/or listen always, respectively. This request is applicable to raw bus files only.

Reset the device or bus, depending on which of the following values is in arg[0]:

Control the interface's response to parallel poll. When the interface is not acting as active controller, it can be enabled to respond to parallel polling by the current active controller. If arg[0] is nonzero, the interface responds to parallel poll. arg[1] specifies the DIO line on which the card responds; arg[1] has a value between 0 and 7, with a value of 0 mapping to DIO1, 1 mapping to DIO2, and so forth. The parallel poll sense of the response is determined by arg[2]. An arg[0] of zero disables the interface's response to parallel poll.

For auto-addressed files, the file's associated device address is configured, rather than the interface.

Enable or disable response to parallel poll. If arg[0] is nonzero, the interface responds to parallel poll. An arg[0] of zero disables the interface's response. This differs from the previous request, because the parallel poll sense and address of the interface's response are unchanged. This request applies to raw bus files only.

Place a device into or out of the remote state. For a raw bus file, this request merely sets or clears the Remote Enable line, depending on whether arg[0] is nonzero or zero respectively. For auto-addressed files, a nonzero arg[0] asserts the Remote Enable line and addresses the device. If arg[0] is zero, the device is removed from the remote state by sending it a Go-to-Local command (GTL).

Request service. This request causes the interface to assert the Service Request line (SRQ) until it is serially polled. At that time it responds with the status byte given in arg[1]. This request applies to raw bus files only.

This request is normally used only when the interface is not the active controller. Nonetheless, the active controller can assert SRQ, and the HPIB_BUS_STATUS request will reflect the assertion; however, the SRQ line does not change state until the interface passes control.

Pass active control of the bus. If the interface is currently active controller, this request relinquishes control of the bus, passing it instead to the device at the bus address in arg[0]. Passing control should be done with care, since it is not possible to detect whether the named device can indeed assume bus control. This request applies only to raw bus files.

Become active controller. This request causes the interface to assert Interface Clear (IFC) and Remote Enable (REN) as a means of regaining control of the HP-IB. It applies only to raw bus files.

Return the bus address associated with the file in arg[0].

Return the interface's timeout in microseconds in arg[0].

Return the interface's path width in bits in arg[0].

Return the interface's data transfer rate in K-bytes per second in arg[0].

Return the interface's read termination pattern in arg[0]; if pattern matching is not enabled, arg[0] holds a -1.

Return the reason for the last signal. This request returns a mask in arg[0], with bits set indicating the reason(s) for the last SIGEMT sent to the user process. Bit definitions are identical to those of the corresponding IO_CONTROL request.

Return lock status. If the device is locked to a process, return that process ID in arg[0] and the interface lock count in arg[1]. If the device is not locked, arg[0] holds a -1.

Return end conditions for the last read from this device or bus. This request returns a byte in arg[0], with a mask of reason(s) for the completion of the last read from the device or raw bus. Applicable bits are:

Conduct a parallel poll. This request returns the bus response to parallel poll in the least significant byte of arg[0], with DIO1 corresponding to the least significant bit. The driver delays at least 100 microseconds before reading the poll response, thus allowing the use of HPIB_PPOLL on systems with extended buses. This request applies to both auto-addressed and raw bus files.

Conduct a serial poll. For raw bus files, this request conducts a serial poll of the device address in arg[1]; the status byte returned by the device is available in arg[0]. Auto-addressed files ignore any address in arg[1], polling instead the device's predefined address.

Return the status of the HP-IB. This request, applicable to both types of files, returns information related to the current bus state. On return, arg[0] holds a value with bits set indicating:

Wait (sleep) until a given device responds to parallel poll. This request blocks the user until either the user's device responds to parallel poll (for auto-addressed files) or until any enabled devices respond (for raw bus files).

For a raw bus file, arg[1] and arg[2] contain eight-bit masks as defined in the HPIB_SIGNAL_MASK request. The return value of the request in arg[0] shows which devices responded to parallel poll.

For an auto-addressed file, arg[1] specifies the sense of the particular device's assertion. Successful completion of the request implies that the device responded.

Wait (sleep) until any of a set of given states is entered. The event(s) to await are specified by computing the bitwise inclusive OR of the values from the list below, and placing the mask in arg[0]. Applicable bits are:

Note that more than one bit can be set, thereby waiting for any of the events to occur. The return value in arg[0] is modified to show the actual event(s) that ended the wait. This is applicable to raw bus files only.

Return the interface type. This returns one of two values in arg[0]:

Infinite

8 bits

0

Enabled

Disabled

None

Unlocked

TR_NOTERM