question on MDTs
For the minimal cyclic time 250us:
When a cyclic time period has started , and MDT0 has been send by the master.
suddenly, 6 bytes is written in the DPM.
the master gets the 6 bytes, and sends them in MDT1.
Is this understanding right ?
Hello houzenan,The SERCOSIII Master supports in CP3 and CP4 up to 4 MDT and up to 4 AT.
Johnny
Is ver11 the latest? ver11 said only AT0 and MDT0 is supported in CP4.
Andreas Jacob
Hilscher Gesellschaft fuer Systemautomation mbH
Yes, Rev11 is the latest one as I know.
For a slave in CP4 , 250us cyclic time:
After its stack recieves the MDT ,
will the data be immediately write to the DPM ?
or waiting for the ending of this cycle to write to the DPM ?
Andreas Jacob
Hilscher Gesellschaft fuer Systemautomation mbH
I think the stack will write the data after the end of the cycle into the DPM.
Hello houzenan,
the Hilscher Master supports up to 4 MDTs and up to 4 ATs. This is correct.
The current version of the Hilscher Slave only supports the constellation of 1 MDT (named MDT0) and 1 AT (named AT0).
In SERCOS the master writes the data for the slaves into the MDTs. The ATs are sent empty (filled with 0).
The slave reads the data from the MDTs and inserts the data for the master into the ATs.
So the principle is: Master writes MDT, reads AT
Slave reads MDT, writes AT.
(If cross communication is used (currently not supported be Hilscher Master and Slave) the slave also reads from the AT.)
On SLAVE side (I guess this was the question) the data is written into the DPM as soon at is requested by the host.
The Hilscher DPM uses a handshake mechanism (described in the netX DPM Interface Manual in detail).
In general:
1.) Host toggles Handshake -> announces read request
2.) netX gets interrupt, copies received data into DPM, acknowledges Handshake
3.) Host gets interrupt and can process the received data
Johnny
Thank you AJ! Thank you Johnny!
When host toggles Handshake but the slave have not recieved the new MDT0,
the earlier-received MDT0 data will be written to the DPM.
Right?
However, the slave do not know that the data is earlier-received .
Or :
the stack do not acknowledge the host, until the new data is available.
Hence, the host get the "fresh" data.
Hello houzenan,
the current version of the Hilscher SERCOSIII slave firmware has a Triple Buffer inside.
The host reads ALWAYS the last (valid) data which was received from the master (MDT).
The slave sends ALWAYS the last data which was written by the Host (AT).
If a MDT is not received yet or has a broken CRC, the data from the last cycle is copied into the DPM.
Johnny
Hi,
If a MDT is not received yet or has a broken CRC, the data from the last cycle is copied into the DPM.
The result of this "buffered controled mode" is the same as "unbuffered uncontroled mode",
For this "buffered controled mode" cannot announce the new data's arrival .
Is there a way that interrupt the Host when new data is coming ?
Hello houzenan,
the modus "buffered controled" guarantees, that the process data is always consistent.
In the uncontroled mode is no synchronisation between host and netX, so host could read while netX writes and vice versa. So there is only byte consistence.
In the current version of the Slave firmware is no support to interrupt the master if new data is received. We work on a new version which will support this, but work is in progress.
Johnny
In the current version of the Slave firmware is no support to interrupt the master if new data is received. We work on a new version which will support this, but work is in progress.
Hello Johnny ! I have download the new version CToolKit ( Revision V1.0.0.0 / 05/18/2010 ). According to the function,
static void ProcessIOArea ( ) ------ cifXInterrupt.c
It seems that the new data arrive interrupt mechanism you have mensioned ( upper quote ) is supported in the CToolKit. Right??
Another question :
Which version of Ethernet/IP firmware supports this mechanism ?
V2.1.19 or other ?
Benjamin Meyer
Hilscher Gesellschaft fuer Systemautomation mbH
Another question :
Which version of Ethernet/IP firmware supports this mechanism ?
V2.1.19 or other ?
you should ask this question in the forum for ethernet ip...
That's great !!! :D :D :D
My project will last a few years , and I have to use this new feather .
Your R&D team is innovative !!! You are really GREAT!
Andreas Jacob
Hilscher Gesellschaft fuer Systemautomation mbH
Hi houzenan,
please download the latest SERCOS III Slave API manual from the Hilscher web page. At page 51 of the Rev11 of the manual you will find the description.