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
Status Word Memory Type (see Status
Word Memory Type Codes table below)
Word 3, chosen by user (see
Memory Type Codes table, below)
Maximum Communication Time
Word 7, see Command Code Table
Parameter Data Size, in bytes
Memory Type for Host Controller Data
Word 9, chosen by user (see
Memory Type Codes table, below)
Start of Host Controller Data (Data Offset)
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
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