Failed to read register: Input/output error

[patlican23]

Steps to reproduce the errors;

sudo /etc/init.d/ethercat start
sudo /etc/init.d/ethercat restart

'Shutting down EtherCAT master 1.6.0  done
Starting EtherCAT master 1.6.0  done'
sudo ethercat slaves
'
0  0:0  PREOP  +  EK1100 EtherCAT-Koppler (2A E-Bus)
1  0:1  PREOP  +  EL1809 16K. Dig. Eingang 24V, 3ms
2  0:2  PREOP  +  EL2809 16K. Dig. Ausgang 24V, 0.5A
'
sudo ethercat state OP
sudo ethercat slaves # all slaves are in OP states
'
0  0:0  OP  +  EK1100 EtherCAT-Koppler (2A E-Bus)
1  0:1  OP  +  EL1809 16K. Dig. Eingang 24V, 3ms
2  0:2  OP  +  EL2809 16K. Dig. Ausgang 24V, 0.5A
'
# Try to read register 0x7001 from the first slave
sudo ethercat reg_read -p0 0x7001 1
# Error encountered:
# Failed to read register: Input/output error

# Try to write value 3 to register 0x7001 on the second slave
sudo ethercat reg_write -p2 0x7001 3
# Error encountered:
# Failed to open '3'!

# Try to write value 1 to register 0x7001 on the second slave
sudo ethercat reg_write -p2 0x7001 1
# Error encountered:
# Failed to open '1'!

[patlican23]

I do not know if this is related but I have also following error when I run;
ros2 run ethercat_manager ethercat_sdo_srv_server
[ERROR] [1721872833.017308282] [ethercat_manager]: Failed to upload SDO: Protocol not supported