Data Communications with the Watlow Series 988 Family
Appendix
A.1
Errors
Errors
Handling Communication Error Codes (ER2)
All communications-related error codes are ER2 error codes, that is, they are not
considered cause for a shutdown of the unit itself. There is always a communica-
tions error code generated when a <NAK> character is sent under ANSI X3.28
protocol. With XON/XOFF flow control, error codes may be generated, but there
will be no standard indication of this fact.
When your message is "not acknowledged" (NAK) in RS-422 or EIA-485 with ANSI
X3.28 Protocol, you may clear ER2 codes by reading it. Use the " ? <sp> ER2
<cr>" command.
Then try the message again; you may have made a syntax error. See the ER2
error code list in Chapters 5, 6 and 7.
With XON/XOFF protocol and the RS-232 interface, the Series 981-984, 986-989
and 996-999 sends no feedback on commands. Therefore, you may want to query
the status of ER2 after each command you send.
User Responsibility
ç
Users must refrain from altering prompts that do not appear on the controller's front
panel or are not included on the specific model. For example, do not send an A2LO
command to a unit not equipped with an alarm for output 2.
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CAUTION:
Sending commands
to a particular
controller for which
it is not equipped
may cause damage
to equipment and/or
processes.
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CAUTION:
Avoid writing <=>
continuously, such
as ramping set
points or repetitive
loops, to the
controller's
EEPROM memory.
Continuous writes
may result in
premature control
failure, system
downtime and
damage to pro-
cesses and equip-
ment.
Appendix
