Parker PDHX-E Series User Manual page 55

• The status request command (R) can be used to provide helpful diagnostics. The
responses generated by the interface are as follows:
*R<CR> - ready for a command with no errors
*S<CR> - ready for a command with function error
*T<CR> - ready for a command with previous comms error
*U<CR> - ready for a command with function error and previous comms error
*B<CR> - busy performing a move with no errors
*C<CR> - busy performing a move with function error
*D<CR> - busy performing a move with previous comms error
*E<CR> - busy performing a move with function error and previous comms error
• The average execution time of commands is approximately 1.5ms. The execution time
is dependent upon the activity of the indexer. When performing a move, especially
during acceleration and deceleration, there is generally less time available for command
execution. This time will delay the execution of subsequent commands, and hence
reduce the rate at which the command input buffer is cleared.
• The interface will correctly respond to XON/XOFF protocol, but will not be able to
generate the XON/XOFF signals when the command input buffer is full.
• If the control program does not use the echo back facility provided by the interface it
may be disabled by sending the command SSA1. This will speed up the character
handling routine a little, but will stop any commands from being transmitted to axes
further down the chain, so should be used with care.
The fact that a routine that breaks some of these rules 'works' is irrelevant. Worst case
communication response conditions may involve a number of coincidences such as sending
a status request just as the interface hits a limit, just as it starts to decelerate, just as the
servo is responding to a load glitch etc. Any motion control requirement explicitly takes
priority over communications under these circumstances and can therefore cause a
communication problem unless you wait for echoback.
If the Controller echoback is turned off by accident, causing an apparent loss of
communication (hanging), it may be re-enabled by typing the following sequence:
CTRL-Q<space>E<space>1R<carriage return>
Note:
[1] This sequence is case sensitive - make sure you are in upper case.
[2] CTRL-Q means hold the 'control' key down and press the Q key at the same time.
This sends the X-ON ASCII character. The Controller obeys the X-ON X-OFF
communications protocol which is used to hold up communications if an interface is sending
too much data too quickly. This means that if X-OFF is sent down the chain (the character
CTRL-S) all communications from the axes stop until CTRL-Q (X-ON) is sent down the chain.
This includes echoback of commands. If CTRL-Q is never sent the system will 'hang'.
[3] You may type CTRL-S by mistake. This condition can be cleared by cycling the power.
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