Is reading one register and a set of registers, from a host, an atomic operation?

[Soder]

Hi,

 

I am working on a host application where I have to read a set of register from the PMAC.

 

My questions are:

1. Is reading/writing a single register from the host atomic in the PMAC?

Or is it possible that a register is half-written when it's read?

 

2. Is reading a set of registers from the host atomic? for example:

RL$004000 5

 

Or is it possible that a PLC/Motion program in between reads/writes any of the individual registers addressed?

 

EDIT: This is done over TCP with ASCII communication.

 

Thanks!

[curtwilson]

Single operations to access a full 24-bit or 48-bit register are atomic in PMAC, so there is no concern that it could be interrupted in the middle and get a partially changed value.

 

However, accesses to multiple registers as in your command are not atomic, so you would need to create a mechanism yourself to ensure a coherent set of data. Our DPRAM data exchange functions do provide mechanisms of this type.