E 75) – ProSoft Technology MVI69-EGD User Manual
Page 75
Reference MVI69-EGD
♦ CompactLogix or MicroLogix Platform
GE Ethernet Global Data Communication Module
ProSoft Technology, Inc.
Page 75 of 96
November 3, 2008
Masked Write PDUs
PDU Type = 36
Mask Write Request
The masked write request PDU is used to change individual bits in one or more
bytes in the destination controller. The header defines parameters which apply to
the all of the individual cell references in the message. Each cell reference
specifies which bits to change in the byte specified by the offset given. Based on
the address type, the Domain ID must contain an Exchange and Producer ID or
target-specific address which is valid on the destination node. A masked write
request sent from a requesting node must be followed by a masked write
response message from the responding node. Some devices may not support
writing individual bits and others may support writing only one bit at a time. Such
devices shall return a status of MEMORY_ACCESS_ERROR for masked write
attempts that they do not support.
Packet
Info
Description Data
Source Port:
7937 (0x 1F01)
Destination Port:
7937 (0x 1F01)
Length:
xx bytes (0x 00 XX)
Checksum:
xxxxx (0x XX XX)
EGD's PDU Field: Offset
Bytes
Hex code
PDU Type:
0
1
0x 24
Message Flag:
1
1
0x HH
Request ID:
2
2
0x HH HH
PVN1:
4
1
0x 01
Option Type:
5
1
0x HH
Message Length:
6
2
0x HH HH
Configuration
Signature:
8
2
0x HH HH
Address Type:
10
1
0x HH
Cell Count:
11
1
0x HH
Producer ID:
12
4
0x HH HH HH HH
Exchange ID:
16
4
0x HH HH HH HH
Time Stamp:
20
8
0x HH . . . HH
UDP
EGD:
Reserved:
28
4
0x HH HH HH HH
The following three items are referred to as the exchange Cell. Each Cell
targets one [EGD Exchange] command line present in the EGD Module's
configuration file.
Offset: writes into the DB Register specified in the [EGD Exchange]
command line.
Mask: example 0x AA AA. Bin 1010101010101010
Data: is ANDed with the Mask Bytes on the target server.
Offset:
32
4
0x HH HH HH HH
Mask:
36
2
0x HH HH
Data:
38
2
0x HH HH