PLC-5 Block Transfers

[toont]

Hi!

I have a general question about Block Transfers. If, say, you want to use I/O 10-17 for the transfers, but also for normal I/O communication, how do you know which I/O is used by the Block Transfers?
I know the first output byte in the configured rack is used as a BT status byte, but is other I/O also used by the BT's?

 

[Ken Roach]

Block transfers use the low byte of the discrete I/O memory word for a given RIO Group, both Input and Output.

So if you have a device at Rack 1, Group 0 then the addresses I:010/00-07 and O:010/00-07 will be reserved for block transfer use.

Addresses I:010/10-17 and O:010/10-17 should be available for general purpose I/O functions.

Are you using a block transfer module inside an actual A-B 1771 series chassis, or a module that emulates a RIO adapter ?

 

[toont]

Thank you for your explanation
Am using a PLC-5/80 inside a "1771-A1B B" chassis.