System Properties Of The Cpu 821Xnet - Adam 821x Manual

CPU ADAM 821x

System properties of the CPU 821xNET

Note
General
Note only for H1
Note only for
TCP/IP
ADAM 8000 Manual CPU 821x – Rev 1.1
System properties of a CP should not be regarded as restrictions or
equated with malfunctions. Certain functions can not be provided or are not
desired when the overall system is taken into account.
The boot time of the CP section of the CPU 821xNET is app. 18 seconds.
The integrated SYNCHRON block (delay time 30s) caters for this boot time.
• Jobs with a priority 0/1 may transmit and/or receive a maximum quantity
of data as defined by the SYNCHRON-HTB. Jobs of this priority are not
blocked. This results in a maximum data transfer rate of 512Byte per job
for a block size of 255 (refer also to block size).
• RECEIVE jobs that are mapped to the communication type "broadcast"
cannot receive all data messages from a fast cyclic transmitter. Messa-
ges that have not been received are discarded.
• The default length (-1, 0xFFFF) is not permitted for the ORG format
length, i.e. the user has to define the exact length of the data that will be
received.
• Jobs with a priority of 1 may send and/or receive a maximum quantity of
data as defined by the SYNCHRON-HTB. Jobs of this priority are not
blocked. This results in a maximum data transfer rate of 512Byte per job
for a block size of 255 (see also block size).
• RECEIVE-jobs that mapped to communication type UDP cannot receive
all data messages from a fast cyclic station. Messages that have not
been received are discarded.
The TCP/IP protocol stack has a global buffer pool where the receive and
transmit buffers are located. This is where system collisions can occur if:
• Data for a receive job is not collected. After a period of time a lack of
resources will occur and the other connections will terminate
themselves.
It is only possible to re-establish proper communications when the
receive buffers of this connection have been released (connection
terminated) or when the data has been retrieved by means of RECEIVE.
• one or more cyclic stations place a load on a CP. When resource
bottlenecks are encountered, the CP can also initiate the termination of
connections.
Chapter 4 Deployment of the CPU 821xNET
4-29