Chapter 6. COMMREQ/Data_Init_Comm Programming
GFK-2892F
March 2019
51
6.3
COMMREQ Command Block Format
The first step in programming communications requests is to set up the contents of the COMMREQ instruction.
This can be done using Block Moves or similar program instructions, as shown later in this chapter.
CPU Memory
Application Program
Command Block
Edit content of COMMREQ
Data is placed in adjacent locations in CPU memory to form a Command Block, per the format shown below:
Location
Data Field
Value
address
Data Block
Length
a 1
Wait/No Wait Flag
Always 0
a 2
Status Pointer Memory Type
a 3
Status Pointer Offset
a 4
Idle Timeout Value (ms)
Always 0
a 5
Max. Communication Time (ms) Always 0
a 6 to
a 78
Data Block
The length of the Command Block depends on the type of COMMREQ being sent. Seventy words is the
maximum and is used only for a COMMREQ that transfers a 128
–
byte datagram. Most Command Blocks are
much shorter. The table in Section 6.3.3 gives an overview of the contents of each type of COMMREQ that may
be sent to a PROFINET Controller for transfer to a Genius Gateway.
