[Etherlab-users] User mode "Register" access methods

[Moebius, Volker]

Hi Richard,

thank you for your quick response!

The functions `ecrt_reg_request_read` and  `ecrt_reg_request_write` are documented as

_This method is meant to be called in realtime context (after master activation)_

Don't they work before the master isn't activated? The `reg_*` methods of the CLI seem to work independently from the master activation!?

> -----Original Message-----
> From: Richard Hacker <ha at igh.de>
> Sent: Wednesday, April 22, 2026 4:31 PM
> To: Moebius, Volker <Volker.Moebius at baader.com>; etherlab-
> users at etherlab.org
> Subject: Re: [Etherlab-users] User mode "Register" access methods
>
> The 'ecrt_reg_*' family of functions in the C-API mirror the 'reg_*'
> functions of the CLI tool.
>
> The ESC registers are reserved for the master. As an EtherCAT user, you do not
> need to touch them.
>
>
>
> On Wed, 2026-04-22 at 14:16 +0000, Moebius, Volker wrote:
> >
> >
> >
> > Hello everyone,
> >
> > The `ethercat` CLI tool implements the "Register Access" functions
> > `reg_read` and `reg_write`. These functions are using
> > EC_IOCTL_SLAVE_REG_READ and EC_IOCTL_SLAVE_REG_WRITE to execute
> these
> > methods. (lines 433ff of tool/MasterDevice.cpp)
> >
> > Is there a reason why possibly corresponding methods for "Register
> > Read" and "Register Write" aren't implemented in the "normal" user
> > mode C API (include/ecrt.h)? Don't these methods make sense for
> > controlling EtherCAT slaves?
> >
> > I'm unfortunately not an EtherCAT expert and I'm confused about the
> > different data objects and communication objects. Are the functions
> > `ecrt_slave_config_create_reg_request`, `ecrt_reg_request_data`,
> > `ecrt_reg_request_state`, `ecrt_reg_request_write` and
> > `ecrt_reg_request_read` related to the same "Register Access" ("Slave
> > Registers") as implemented by the CLI? Or do they manage a different
> > kind of registers?
> >
> > .
>
> --
> Mit freundlichem Gruß / Best regards,
> Richard Hacker
> --
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> Richard Hacker, M.Sc.
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