Parker PDHX-E Series User Manual page 96

No communication
Perhaps the commonest controller problem, especially during initial commissioning, is
apparent lack of communication with the terminal or host controller.
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.
[4] The E command is the enable RS-232 command which can easily be mis-typed as
the F command which will lock out the keyboard. Cycling the power will not cure this problem
since SV cannot be typed following a keyboard lock out.
Certain 'tidy up' commands can be useful. For example:
• If you are not getting the typed characters echoed back you may need to use the SSA0
command.
• To get a prompt ($ or >) you may need to use the EX1 command.
• To get out of a $ prompt (indicating a sequence definition) type XT.
• If buffered commands are being ignored, type S in case the indexer is busy. You
should avoid typing Z or cycling the power.
In summary:
• Don't type CTRL-S
• Don't type the command F
• Don't address a non-existent axis
• Don't rubout a device address
• Type carefully
None of the above conditions is an error so the status LED on the Controller will not indicate a
fault and the axis may well be energised or even moving.
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