NAME

hpib_ppoll − conduct parallel poll on HP-IB bus

SYNOPSIS

int hpib_ppoll (eid);
int eid;

DESCRIPTION

Hpib_ppoll conducts a parallel poll on an HP-IB bus.  Eid is an entity identifier of an open HP-IB raw bus device file obtained from an open(2), dup(2), fcntl(2), or creat(2) call. 

Devices  enabled to  respond  and that are in need of service can then assert the  appropriate  DIO line.  This enables the controller to determine  which devices, if any, need service at a given time.  Hpib_ppoll delays for 25 microseconds before returning  with the response.  The  interface  must be the active controller to conduct a parallel poll. 

RETURN VALUE

Hpib_ppoll returns an integer value whose least significant byte corresponds to the byte formed by the 8 data input/output (DIO) lines.  Devices  enabled to respond to a parallel  poll do so on the  appropriate DIO line.  DIO line 0 corresponds to the least  significant  bit in the response  byte.  A −1 return  value  indicates  that an error occurred. 

ERRORS

Hpib_ppoll fails under the following situations, and sets errno (see errno(2)) to the value in square brackets:

­[EBADF] eid does not refer to an open file. 

­[ENOTTY] eid does not refer to an HP-IB raw bus device file. 

­[EIO] the interface is not current the active controller. 

AUTHOR

Hpib_ppoll was developed by the Hewlett-Packard Company. 

Hewlett-Packard Company  —  Version B.1,  April 12, 1993