Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 242)

Chapter
Call Routines 0–68 12
12 -52
7. The BASIC module assembles the DH-485 packet and sends it to the
remote device on the DH-485 network
BASIC Module
Remote Device
DH485 DH-485 Network
DATA BUFFER
8. The BASIC module places the DH-485 transfer status into the BTR
buffer word 1.
PLC Processor
BASIC Module
PLC Backplane
BTR Buffer
Status 1 Reserved
9. The BASIC module sets the input image table, bit 16 to inform the
local PLC processor that valid data is transferred and the status of the
transfer is available. The PLC performs a block transfer to retrieve
the status.
PLC Processor
BASIC Module
PLC Backplane
Set Input
Table Bit 16
10. The BASIC module detects a successful block transfer and resets the
input image table, bit 16.
PLC Processor
BASIC Module
PLC Backplane
Reset Input
Image Table
Bit 16