[etherlab-users] Unable to write servo drive control word

[Jan Thogersen]

Hi all,

I'm very new to the world of EtherCat so please excuse me if the question
is 'dumb'.

I'm a CNC hobbyist that was so lucky to stumble upon 3 Mitsubishi servo
drives with EtherCat option. I've been trying to get the drive to respond
via EtherCat and I have partial successful.
I can read parameters however I can't write them. Not being able to write
parameter also prevent me from setting the drive to operational mode.

Details:
Drive: Mitsubishi MR-J3-40A-RJ158
Master: IgH EtherCAT master 1.5.2 2eff7c993a63
NIC: e100e (Intel pro/1000)

Here is what I do:
I set an alias
"ethercat alias -p 0x0 0x1"

I set the drive to OP mode
"ethercat states -p 0 op"

I read the sdos to verify that the object directory is received (see
attachment)
"ethercat sdos -v"

I can read the status word
"ethercat upload -p 0 0x6041 0"
response: "0x4070 16496"

"ethercat upload -p 0 0x6040 0"
response: "0x0 0"

Then I try to clear" via the writable register 0x6040.
"sudo ethercat download -p 0 -a 1 -t uint16 0x6040 0x8"
response: "SDO transfer aborted with code 0x06020000: This object does not
exist in the object directory".

or with subindex
"sudo ethercat download -p 0 -a 1 -t int16 0x6040 0x0 0x8"
response: "SDO transfer aborted with code 0x06010000: Unsupported access to
an object"

What am I doing wrong? Why can't I write to the register?

Any help or hints are highly appreciated!

Best regards
Jan Thogersen

[Mohsen Alizadeh Noghani]

Hi Jan.
I don't think requesting OP mode is a good idea. Drive configuration (e.g.
setting the control word) is often done in the PRE-OP state, which, if the
master module is active, is automatically requested.
Additionally, even if you do enter OP mode, you have to continually send
frames in order to "sustain" it. We only enter OP mode when we start giving
position command to drives.
Therefore, I suggest you try writing the controlword, with subindex, after
loading the master module (/etc/init.d/ethercat start). No additional
commands should be necessary.
Best,
Mohsen

[Dr.-Ing. Wilhelm Hagemeister]

Hallo Jan,

to clarify Mohsen response; you need an application which exchanges data
cyclically. One can't get a drive or slave to "Operational" or write and
read PDOS only with the ethercat command. See the example section in the
ethercat repo for examples.

Regards Wilhelm.