User manual

5
Chapter
5-1
Commands
Read this chapter to understand the command interface to the PLC-5/VME
processor. The orientation of this chapter is based on a driver program
running on a separate CPU module communicating with the processor.
Unless otherwise noted, all multiple-byte numerical fields are represented
in big-endian (Motorola) format, meaning that the most-significant data
byte appears in the lowest-addressed byte.
There are four types of commands:
Command Command
Word
Definition
Continuous Copy
to VME
0001H Instructs the PLC-5/VME processor to copy processor file
memory to VMEbus memory once per scan cycle of the
processor
.
It is similar in definition to the corresponding command in the
6008-LTV processor.
Continuous Copy
from VME
0002H Instructs the PLC-5/VME processor to copy VMEbus memory
to the processor file memory once per scan cycle.
Handle Interrupts 0003H Defines which VMEbus interrupts the PLC-5/VME processor
behaves as an interrupt handler.
Send PCCC FFFFH Sends a command packet containing a standard PCCC.
These were referred to as “selective” commands in the
6008-LTV processor.
Chapter Objectives
Command Types