Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 147)

9–9 Diagnostic Counters
Publication 1770Ć6.5.16 - October 1996
This counter byte Counts the number of
9
Frames that were rejected because they were less than 6 bytes
long.
This counter records all status frames that were received by a node
that disabled its address recognizer in the second step of the
mastership timeout process. This happens often on a
heavilyĆloaded link.
10
Frames that were rejected because the destination address was
incorrect.
This can have the same cause as counter byte 9. This counter also
detects frames that have the same source and destination address.
11
Times that the receiver sent an ACK without first being able to
allocate a receive buffer.
This may result in a memory overflow error when the next message
is received.
12
Frames that were rejected because of a bad CRC.
This error is common on a noisy link.
13 Times a message was received that contained more than 250 bytes.
14
Times a message was received when buffer space was not
allocated for it.
This usually follows a memory full" error.
15
Duplicate frames received.
A duplicate frame is sent by a transmitter when it fails to receive an
ACK. If the reason it failed to receive an ACK was that the ACK was
lostĊrather than because the original message was lostĊ
the duplicate is redundant and should be discarded. Any two
successive messages between polls that have the same sequence
number fields and the same command or reply bits are assumed to
be duplicates.
16
Aborts received.
The HDLC abort signal is not used on a DH link but can be detected
by the serial input or output, in certain circumstances. Some nodes
whose addresses match the ringing pattern after a transmitter
shutoff can be particularly susceptible to this error (nodes 36, 76,
and 176, for example). These numbers depend on highway
configurations.
17, 18 Messages successfully transmitted.
19, 20 Messages successfully received.