I would like to understand the limitation of our hardware regarding SafeDomain - SafeDomain Communication.
Lets say we take X20SLX811 as an example, In the datasheet we can see that it is capable of connecting to 1 Managing SafeDomain only. But it can also be the Managing SafeDomain in the network.
When it is the Managing SafeDomain, it is capable of exchanging 8 bytes of data in each direction (in and out). However, what is the limiting factor here? How many Connected SD can i have connected to this Managing SD?
Are connected SD considered as a Safe Node hence using the Hardware’s “Max. number of SafeNODEs” as the limiting factor?
Or the limitation is only on the network bandwidth as such it is not hardware dependent (X20SLX811 would have the same limit as a X20SL8110)? So in theory it would be the limit of SD IDs (limit of UDINT)?
Use X20SLX for: basic safety requirements. NOT for centralized safe domains.
Use X20SL81 for: advanced safety functions and centralized safe domains.
SLX to SLX communication is new form Automation Runtiome 4.9 ** for some** SLX devices, not ALL. This is one good sing to pay attention carefully to use SLX for this purpose.
In this section of the help (B&R Online Help) States:
Max. number of SafeNODEs 10 This includes the SLX itself
So, here you have the first limiting factor, by the hardware itsef. But additionally there are software limitations, regarding the data shared: B&R Online Help (br-automation.com)
More information about Safe Domains and this limit.
A SafeDOMAIN takes over the task of safe configuration management, i.e. it ensures proper configuration and safety-related monitoring of the UDID of the remote station. This SafeDOMAIN is referred to as the “Managing SafeDOMAIN” . (->Source)
Having a look in the SLX, the limitation is just one! So it means that SLX is not a right HW to centralize and manage the safe comunciation between different areas.
X20SL8110 has different limit, in fact is 20. But remember that depending of the amount of variables this value could go down. B&R Online Help (br-automation.com)
The rule of the thumb:
Use X20SLX for: basic safety requirements. NOT for centralized safe domains.
Use X20SL81 for: advanced safety functions and centralized safe domains.
Thanks for the detailed explanation! That is very clear for me now. I just have one additional question here.
Since the limitation is on the I/O buffer mainly, if we have lets say more than 20 Safe Domains lets just say 100 Safe Domains, should our solution involve say like 5x X20SL81xx essentially having 5 different network (or should I say “Centralized Safe Domain Network”)?
