Configuration
4.7 SNMP
CP 1243-1
Operating Instructions, 04/2017, C79000-G8976-C365-03
53
Acknowledgment mechanism for the IEC protocol
With each sent data frame, the CP sends a continuous send sequence number. The data
frame remains initially stored in the send buffer.
When it receives the data frame, the master sends the send sequence number from this or
(if several frames are received) the last frame as an acknowledgement to the CP. The CP
saves the send sequence number returned by the master as a receive sequence number
and uses it as an acknowledgement.
Frames whose send sequence number is equal to or lower than the current receive
sequence number are evaluated as having been successfully transferred and are deleted
from the send buffer of the CP.
Recommendations of the specification:
● w should not be higher than 2/3 of k.
● Recommended value for k: 12
● Recommended value for w: 8
The CP supports the following SNMP versions:
●
Available with security functions disabled.
Note that with this read and write access to the module is possible. In this case, other
settings are not possible.
The configuration of the community strings is only possible if the security functions are
enabled.
The CP uses the following community strings to authenticate access to its SNMP agent
via SNMPv1:
Access to the SNMP agent in the CP
Community string for authentication in SNMPv1
*)
Read and write access private
*) Note the use of lowercase letters!
●
Available only when security functions are enabled
For information on the configuring SNMPv3, refer to the section SNMP (Page 70).
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