Parker PDHX-E Series User Manual page 75

Pause Commands
There are four types of pause commands available as follows:-
Pause and wait for continue command C to continue. A common use of the Buffered Pause
PS is to hold execution of individual commands in a Command Loop until the entire loop has
been loaded.
Tnnn
Pause in processing commands for a given number of seconds and then continue.
U
Hold (pause) now and wait for continue. This is an immediate command.
TRE
Pause in processing commands until the designated TRIGGER condition is met.
Triggers are used to synchronise positioner operations with external events. They can be
used to implement a "handshaking" function with other devices. See command details for
exact syntax.
Status Request Commands
All status request commands result in data being returned to the controller from the
positioner. To prevent multiple positioners from all responding at once, the status request
commands are given the classification "Device Specific" meaning that the device address of
the responding positioner must be placed in front of the command. No positioner will execute
a Device Specific command without its device number.
The use of status request commands must be conducted in an orderly fashion. Commands
should only be issued when the host is ready to read the response. New commands should
not be sent until the response is received. In particular, after a buffered status command, an
immediate status command should not be sent until the response has been received by the
host. If this procedure is not followed, the command responses will be intertwined, rendering
the information useless.
There are two status commands that can be used to request position.
The DPA Command will report how many steps the motor has moved relative to the absolute
zero position. This position is calculated by summing the total number of moves commanded
since the positioner was at the absolute zero position. If position reports are needed that are
relative to the beginning of each individual move, the PR command should be used.
Using the Evaluation Commands
The IF, WHILE and UNTIL commands contain fields that are evaluated to provide conditional
program flow. The evaluation statement is contained in parentheses after the IF, WHILE and
UNTIL commands. A space or underscore (_) indicates each comparison.
IF(condition)..commands..ELSE..commands..NIF
REPEAT..commands..UNTIL(condition)
WHILE(conditional)..commands..NWHILE
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