IEEE1284_GET_DEVICEI(3) Functions IEEE1284_GET_DEVICEI(3)
ieee1284_get_deviceid - retrieve an IEEE 1284 Device ID
ssize_t ieee1284_get_deviceid(struct parport *port, int daisy, int flags, char *buffer,
This function is for retrieving the IEEE 1284 Device ID of the specified device. The
device is specified by the port to which it is attached, and optionally an address (daisy)
on the daisy chain of devices on that port.
daisy should be -1 to indicate that the device is not participating in a IEEE 1284.3 daisy
chain, meaning it is the last (or only) device on the port, or should be a number from 0
to 3 inclusive to indicate that it has the specified daisy chain address (0 is next to the
The flags parameter should be a bitwise union of any flags that the program wants to use.
Available flags are:
Guarantee a fresh Device ID. A cached or OS-provided ID will not be used.
The provided buffer must be at least len bytes long, and will contain the Device ID
including the initial two-byte length field and a terminating zero byte on successful
return, or as much of the above as will fit into the buffer.
A return value less than zero indicates an error as below. Otherwise, the return value is
the number of bytes of buffer that have been filled. A return value equal to the length of
the buffer indicates that the Device ID may be longer than the buffer will allow.
The device did not provide an IEEE 1284 Device ID when interrogated (perhaps by the
operating system if F1284_FRESH was not specified).
One or more of the supplied flags is not supported in this implementation, or if no
flags were supplied then this function is not implemented for this type of port or
this type of system. This can also be returned if a daisy chain address is specified
but daisy chain Device IDs are not yet supported.
F1284_FRESH was specified and the library is unable to access the port to interrogate
There is not enough memory.
There was a problem initializing the port.
The port parameter is invalid.
Unless the F1284_FRESH flag is given, the library will try to find the device's ID as
unobtrusively as possible. First it will ask the operating system if it knows it, and then
it will try actually asking the device for it. Because of this, the Device ID may be
partially computed (the length field, for example) or even partially missing if the
operating system has only remembered some parts of the ID. To guarantee that you are
getting the bytes that the device sent, use F1284_FRESH. Be aware that the operating
system may allow any user to inspect the Device IDs that it provides, whereas device
access is normally more restricted.
The initial two-byte length field is a big-endian 16 bit unsigned integer provided by the
device and may not be accurate. In particular, it is meant to indicate the length of the
entire string including the length field itself; however, some manufacturers exclude the
length field or just set the length field to some arbitrary number greater than the ID
Tim Waugh <email@example.com>
Copyright (C) 2001-2003 Tim Waugh
[FIXME: source] 06/17/2014 IEEE1284_GET_DEVICEI(3)