Beckhoff KL6781, Documentation

Page: 19 / 32

Access from the user program
KL6781 19 Version: 2.0.0
4.2 Control and status word
Process data mode
Control word (in process data mode)
The control word (CW) is located in the output process image [
}
21] , and is transmitted from the controller
to the terminal.
Bit CW.15 CW.14 CW.13 CW.12 CW.11 CW.10 CW.9 CW.8 CW.7 CW.6 CW.5 CW.4 CW.3 CW.2 CW.1 CW.0
Name OL7 OL6 OL5 OL4 OL3 OL2 OL1 OL0 Reg - - - - IR RA TR
Key
Bit Name Description
CW.15 ... CW.
8 OL7 ... OL0
(OutLenght) 1
dec
...
22
dec
Number of output bytes () available for transfer from the
controller to the terminal.
CW.7 Reg (RegAccess) 0
bin
Register communication off (process data mode)
CW.6 ... CW.3 - 0
bin
reserved
CW.2 IR
(InitRequest) 0
bin
The controller once again requests the terminal to prepare for
serial data exchange.
1
bin
The controller requests terminal for initialization. The
transmission and reception functions are disabled, the FIFO
pointers are reset and the interface is initialized with the
values in the appropriate registers. The terminal
acknowledges completion of the initialization via bit
SW.2
[
}
19] (IA).
CW.1 RA
(ReceiveAccepted) toggle The controller acknowledges receipt of data by changing the
state of this bit. Only then new data can be transferred from
the terminal to the controller.
CW.0 TR
(TransmitRequest) toggle Via a change of state of this bit the controller notifies the
terminal that the DataOut bytes contain the number of bytes
indicated via the OL bits. The terminal acknowledges receipt
of the data in the status byte via a change of state of bit
SW.0
[ } 19] (TA). Only now new data can be transferred from the
controller to the terminal.
Status word (in process data mode)
The status word (SW) is located in the input process image [
}
21] , and is transmitted from terminal to the
controller.
Bit SW.15 SW.14 SW.13 SW.12 SW.11 SW.10 SW.9 SW.8 SW.7 SW.6 SW.5 SW.4 SW.3 SW.2 SW.1 SW.0
Name IL7 IL6 IL5 IL4 IL3 IL2 IL1 IL0 Reg - - - BUF_F IA RR TA