System Variable - Siemens SINUMERIK 840D sl Function Manual

B3: Distributed systems - 840D sl only
3.2 NCU link
requests to the other NCUs in the link group (message delays). Causes for a message delay
can be:
● Writing a large number of link variables in an interpolation cycle
● Writing link variables and a the request for an axis container rotation in the same interpolator
cycle
● Writing link variables and transferring an alarm in the same interpolation cycle
3.2.2.5

System variable

NC-specific system variable
Identifier
$AN_LINK_TRANS_RATE_LAST
$AN_LINK_TRANS_RATE_LAST_SUM[<n>]
$AN_LINK_CONN_SIZE_LINKVAR
$AN_LINK_CONN_SND[<n>]
$AN_LINK_CONN_RCV[<n>]
<n>: NCU number according to MD12510 $MN_NCU_LINKNO of the relevant NCU
Note for: $AN_LINK_CONN_SIZE_LINKVAR
The writing of a link variable causes the number of bytes specified in
$AN_LINK_CONN_SIZE_LINKVAR to be transferred via the not-cyclic link communication.
The number is independent of the format of the link variables.
The maximum number of write requests that can be transferred to the specified NCU for each
interpolator cycle is calculated as:
Max. number of write requests = $AN_LINK_CONN_SND[<n>] /
$AN_LINK_CONN_SIZE_LINKVAR
Channelspecific system variable
Identifier
$A_LINK_TRANS_RATE
1) Application example, refer to Section: "Synchronization of a write request (Page 95)"
94
1)
Meaning
The number of write requests that were still free in
the last interpolator cycle.
The number of write requests that were still free in
the last interpolator cycle in the send direction to
the specified NC <n> (NCU number).
The number of bytes to be transferred for a write
request of a link variable.
The maximum number of bytes that can be trans‐
ferred per interpolator cycle from the current NCU
to the specified NCU.
The maximum number of bytes that can be trans‐
ferred per interpolator cycle from the specified
NCU to the current NCU.
Meaning
Number of write requests that still can be transfer‐
red in the current interpolator cycle.
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Extended Functions