Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 311)

Chapter
Call Routines 69–127 13
13 -53
2. The BASIC module transfers the data into the local PLC BTR buffer
and places the byte count into the lower byte of the BTR word 1.
The upper byte of BTR word 1 is reserved.
BASIC Module
BTR BUFFER
BTR Buffer
BYTE
COUNT
Reserved
3. The BASIC module sets the input image table bit 17 to inform the
PLC processor that valid data is available. The BASIC module then
initiates a block transfer read.
PLC Processor
BASIC Module
PLC Backplane
Set Input
Image Table
Bit 17
4. The PLC processor retrieves the data from the block transfer. The
BASIC module detects a successful block transfer and resets the
input image table bit 17 on the same end of scan cycle in which the
block transfer was performed.
PLC Processor
BASIC Module
PLC Backplane
Reset Input
Image Table
Bit 17
This call is active until you re-execute it with different input parameters.
If this occurs, the previous CALL 118 is automatically disabled and the
new CALL 118 takes effect. You cannot execute multiple CALL 118s in
parallel.