On 25 June 2014, quoth taotao:
> I try to build ethercat on ubuntu. Now Ethercat host master has been 
> successfully established.

These sorts of questions really belong on the users list.

> Q1: How can i find slave's alias and position(ec_slave_config_t)?
> i try to use command "/opt/xxx/ethercat sl -v" , but there not have this 
> information.  

It does.  If you run "ethercat slaves" without the -v, you'll see a number on 
the left (this is the absolute ring position, starting from 0) and in the 
second column a N:M pair (this is the relative position from the nearest 
previous device with an alias; if it's showing :0 then that's the alias for the 
device itself).

> Q2: If i just have only one slave (ET1100) , so I just one slave's alias and 
> position, 
> I 'm right?
> Example c file always has four defines ( slave's alias and position).

You can address any slave either as "0, absolute" or as "alias, relative".  
Both work; which one you use just depends on what the requirements of your 
application and network configuration are.

> Q3:  struct ec_pdo_entry_reg_t:
> what is slave alias address?   It is xml (beckoff 's slave configure xml) 
> keyword :startaddress?
> what is slave direction? how can it get this information?

No.  You need to specify which PDOs your application is interested in 
retrieving.  You should already know that from the slave's datasheet, or you 
can look at the defaults using the "ethercat pdos" command.


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