NAME

hpib_spoll − conduct a serial poll on HP-IB bus

SYNOPSIS

int hpib_spoll (eid, ba);
int eid, ba;

DESCRIPTION

Hpib_spoll conducts a serial poll of the specified device.  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.  Ba is the bus address of the intended device. 

Hpib_spoll polls a single device for its response byte.  The information  stored in the response byte is device specific  with  the  exception  of  bit  6.  If bit 6 of  the response byte is set, the addressed device has asserted the SRQ line, and is requesting  service.  (Note that the least significant (right-most) bit of the response byte is bit 0.) 

Not all devices respond to the serial poll function.  Consult the device  documentation.  Specifying a device that does not support  serial polling may cause a timeout  error or suspend your  program  indefinitely (see hpib_rqst_srvce(3I)).  The interface  cannot serial poll itself.  The  interface  must be the active  controller. 

RETURN VALUE

If hpib_spoll is successful, the device response byte is returned in the least significant byte of the return  value.  Otherwise, −1 is returned, indicating an error. 

ERRORS

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

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

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

­[EIO] the device polled did not respond before timeout, or the interface is not the active controller. 

­[EINVAL] ba is the address of the polling interface itself. 

AUTHOR

Hpib_spoll was developed by the Hewlett-Packard Company. 

SEE ALSO

hpib_rqst_srvce(3I). 

Hewlett-Packard Company  —  May 11, 2021