Thanks for the quick reply. I hadn't discovered the ecrt_slave_config*
functions yet but those look a lot easier to use then what I was
imagining setting up with the ...request_write function and state
monitoring. Also thanks for the explanation of SDOs vs PDOs. This helps
a lot.
On 12/17/2015 04:29 PM, Gavin Lambert wrote:
SDOs are just objects that can be accessed via acyclic (mailbox)
transfers. Typically (if the slave supports CoE) all PDOs can be
accessed as SDOs (though usually there’s little point) but only some
SDOs can be accessed as PDOs.
Most of the time SDOs are used purely for configuration – values that
you want to set once on startup and never change again. For this
case, simply use the ecrt_slave_config_sdo* family of functions during
the configuration phase (when you’re registering PDOs) and the library
will take care of sending this to the device.
The ecrt_sdo_request family of functions are for the other kind of SDO
access, where there is something that you want to read or modify
during live operation. This is rarer (except for things like
diagnostic monitoring) as typically live changes are done via PDOs
instead. But sometimes these can be useful if it’s only extremely
rare that you want to change something so you don’t want to “waste”
space in the normal domain transfer.
An SDO transfer will take multiple cycles to execute (absolute minimum
is about 3, but it usually takes more); each slave can only process
one transfer at a time; and the master has a small limit on the number
of concurrent transfers it will actually issue, although it can hold
extras in a queue.
*From:*etherlab-users [mailto:etherlab-users-boun...@etherlab.org] *On
Behalf Of *John Hubbard
*Sent:* Friday, 18 December 2015 11:42
*To:* etherlab-users@etherlab.org
*Subject:* [etherlab-users] EL6688 SDOs
Hello,
I've not gotten my Beckhoff EL1252 and EL2252 modules mostly working
(I've still got some confusion WRT distributed clocks, and I'm still
seeing the warnings/errors I mentioned the other day). I'm now
working on trying to get the EL6688 module (IEEE 1588/Precision Time
Protocol) up and running. From my reading of the Beckhoff
documentation I'm under the impression that most of the setup options
(e.g. Ethernet configuration and PTPv1 vs PTPv2 mode) need to be setup
via SDOs instead of PDOs. (Is this what others would expect?) For
reference I've attached the full SDO dictionary that I obtained via
'ethercat sdos'.
I'm a little unclear what the difference between SDOs and PDOs is. Is
the difference just the PDOs can be read/written every cycle, while
SDOs can only be read/written when ecrt_sdo_request_state ==>
EC_REQUEST_SUCCESS (following an ecrt_sdo_request_write when the state
is UNUSED)? Is there a limit to how many SDOs I can request writes
per cycle? From the example it looks like writing an SDO is done
using the same macro as writing a PDO (i.e. EC_WRITE_U32(some_sdo)),
is that correct?
From the mailing list it looks like there was someone that attempted
to use an EL6688 module back in 2010. Has anyone used one more
recently (i.e. with etherlabs 1.5), and if so do they have any code
snippets that they would be willing/able to share?
Thanks.
--
-john
To be or not to be, that is the question
2b || !2b
(0b10)*(0b1100010) || !(0b10)*(0b1100010)
0b11000100 || !0b11000100
0b11000100 || 0b00111011
0b11111111
255, that is the answer.
--
-john
To be or not to be, that is the question
2b || !2b
(0b10)*(0b1100010) || !(0b10)*(0b1100010)
0b11000100 || !0b11000100
0b11000100 || 0b00111011
0b11111111
255, that is the answer.
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