User Manual
Appendix B
GFK-1742F
Jan 2020
DSM314 Communications Request Instructions
399
B-3.2
The UDT COMM REQ Command Block
Table 84: User Data Table Command Block
User Data TableCOMM REQ Command Block for DSM314 Module
Description
Address Offset Word No. and Value
Data Block Header Length
A 0
Word 1, always set to 4
WAIT/NOWAIT Flag
A 1
Word 2, always set to 0
Status Word Memory Type (see Status
Word Memory Type Codes table below)
A 2
Word 3, chosen by user (see
Memory Type Codes table, below)
Status Pointer Offset
A 3
Word 4, chosen by user
Idle Timeout Value
A 4
Word 5, always set to 0
Maximum Communication Time
A 5
Word 6, always set to 0
Command Code
A 6
Word 7, see Command Code Table
Parameter Data Size, in bytes
A 7
Word 8, always 2048.
Memory Type for Host Controller Data
A 8
Word 9, chosen by user (see
Memory Type Codes table, below)
Start of Host Controller Data (Data Offset) A 9
Word 10, chosen by user
Data Block Length (Word 1): The length of the Data Block header portion of the Command
Block. It should be set to 4. The Data Block header is stored in Words 7 through 10 of the
Command Block
WAIT/NOWAIT Flag (Word 2): This must always be set to logic zero for the DSM.
Status Word Memory Type (Word 3): This word specifies the memory type that will be used
for the Status Word. Each memory type has its own specific code number, shown in the
Memory Type Codes table below. So, for example, if you want to use %R memory for the
Status Word, you would put either the decimal code number 8 or the hexadecimal code
number 08h in this word.
Note that if you select a discrete memory type (%I or %Q), 16 consecutive bits will be
assigned to the Status Word, beginning at the address specified in the Status Word Pointer
Offset word, described below.
Table 85: Status Word Memory Type Codes
Memory Type
Abbreviation
Memory Type
Code Number to Enter
Decimal
Hexadecimal
%I
Discrete input table
70
46h
%Q
Discrete output table
72
48h
%R
Register memory
8
08h
%AI
Analog input table
10
0Ah
%AQ
Analog output table
12
0Ch