PUT / GET don't seem to work asynchronously by just setting REQ to TRUE, like you can with TRCV. Help/manuals allude that you can as there is a link to describing async vs sync operation of blocks, which describes that if REQ is held true, block will automatically retrigger when ready.  But it doesn't work for GET & PUT.

What is simplest way to get fast cyclic comms between PLCs without having to continually re-trigger blocks using S7-1500s & TIA V17. If you have to re-trigger programatically then for 10ms comms you would need to run the task at 5 ms to get a positive edge every 10ms.