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Gpib parallel poll – AMETEK XDL Series II User Manual

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GPIB IEEE Std. 488.2 Error Handling – Query Error Register

The IEEE 488.2

UNTERMINATED

error (addressed to talk with nothing to say) is handled as follows.

If the instrument is addressed to talk and the response formatter is inactive and the input queue is
empty then the

UNTERMINATED

error is generated. This will cause the Query Error bit to be set in

the Standard Event Status Register, a value of 3 to be placed in the Query Error Register and the
parser to be reset. See the Status Reporting section for further information.

The IEEE 488.2

INTERRUPTED

error is handled as follows. If the response formatter is waiting to

send a response message and a

has been read by the parser

or the input queue contains more than one END message then the instrument has been

INTERRUPTED

and an error is generated. This will cause the Query Error bit to be set in the

Standard Event Status Register, a value of 1 to be placed in the Query Error Register and the
response formatter to be reset thus clearing the output queue. The parser will then start parsing
the next

from the input queue. See the Status Reporting section for

further information.

The IEEE 488.2

DEADLOCK

error is handled as follows. If the response formatter is waiting to send

a response message and the input queue becomes full then the instrument enters the

DEADLOCK

state and an error is generated. This will cause the Query Error bit to be set in the Standard Event
Status Register, a value of 2 to be placed in the Query Error Register and the response formatter
to be reset thus clearing the output queue. The parser will then start parsing the next

MESSAGE UNIT>

from the input queue. See the Status Reporting section for further information.

GPIB Parallel Poll

Complete parallel poll capabilities are offered on this instrument. The Parallel Poll Enable
Register is set to specify which bits in the Status Byte Register are to be used to form the

ist

local

message The Parallel Poll Enable Register is set by the *PRE command and read by the
*PRE? command. The value in the Parallel Poll Enable Register is ANDed with the Status Byte
Register; if the result is zero then the value of

ist

is 0 otherwise the value of

ist

is 1.

The instrument must also be configured so that the value of

ist

can be returned to the controller

during a parallel poll operation. The instrument is configured by the controller sending a Parallel
Poll Configure command (PPC) followed by a Parallel Poll Enable command (PPE). The bits in
the PPE command are shown below:

bit 7 =

X

don't care

bit 6 =

1

bit 5 =

1

Parallel poll enable

bit 4 =

0

bit 3 =

Sense sense of the response bit; 0 = low, 1 = high

bit 2 =

?

bit 1 =

?

bit position of the response

bit 0 =

?

To return the RQS bit (bit 6 of the Status Byte Register) as a 1 when true and a 0 when false
in bit position 1 in response to a parallel poll operation send the following commands

*PRE 64

,

then PPC followed by 69H (PPE)

The parallel poll response from the instrument will then be 00H if RQS is 0 and 01H if RQS
is 1.

During parallel poll response the DIO interface lines are resistively terminated (passive
termination). This allows multiple devices to share the same response bit position in either wired-
AND or wired-OR configuration, see IEEE 488.1 for more information.