Watlow Series 734 Data Communications - Manual (Page 20)

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WATLOW Series 733/734 How to Use Data Communications
NAKs and Error Codes
When your message is "not acknowledged" (NAK) in EIA/TIA-422 or EIA/TIA-485
with ANSI X3.28 Protocol, you may clear ER2 codes by reading it. That is, use "?"
Then try the message again; you may have made a syntax error. See the error
code listing in Table 5, page 17.
With XON/XOFF protocol and the EIA/TIA-423 interface, the 733/734 sends no
feedback on commands. Therefore, you may want to query the status of ER2 after
each command you send.
All communications-related error codes are ER2 error codes, that is they are not
considered cause for a shutdown of the 733/734 unit itself. There is always a
communications error code generated when a character is sent under the
ANSI X3.28. With XON/XOFF flow control error codes may be generated, but
there will be no standard indication of this fact.
User Responsibility
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All data communications commands are available on all models of the Series 733/
734 which have communications capability. Users must refrain from altering
prompts which do not appear on the Series 733/734 front panel. For example, do
not send an A1LO command, page 17, to a Series 733/734 not equipped with
alarm outputs.
The exception to this rule concerns the MENU command, which requires valid data
for SP2 (Set Point 2) and events, even though the hardware is not present in the
particular Series 733/734.
Errors
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CAUTION:
Sending commands
to a particular
Series 733/734 for
which it is not
equipped may cause
damage to equip-
ment and/or
processes.