Rockwell Automation 1747-L55x,D174710.4 SLC 500 Ethernet User Manual
Page 35
4–5
Communicating on the Ethernet Network
Publication 1747-10.4
SLC 5/05 Channel 1 (Ethernet port)
MSG Control Block with Logical ASCII Addressing
valid for PLC-5 typed read or write only
WORD
15
14
13
12
11
10
09
08
07
06
05
04
03
02
01
00
0
EN
ST
DN
ER
CO
EW
NR
TO
Error Code
1
Reserved (Target Node Not Used)
2
Number of Elements
3
Not Used
4
File Type (based on local source or destination address)
5
Not Used
6
Not Used
7
Reserved (Internal Messaging Bits)
WQ
8
Message Timer Preset
9
Message Timer Scaled Zero
10
Message Timer Accumulator
11
Data Length in Bytes
12
AO=1
Reserved (Internal Messaging Bits)
Reserved
13
Reserved
14
Logical ASCII Address String Length including NULL Termination Character (bytes)
15
First Byte of ASCII Address String
Second Byte of ASCII Address String
16
Third Byte of ASCII Address String
…
…
…
…
…
55
Eighty-First Byte of ASCII Address String
NULL Byte of Longest ASCII Address String
56
First Byte of IP Address String
➀
Second Byte of IP Address String
57
Third Byte of IP Address String
…
…
…
…
…
76
Forty-First Byte of IP Address String
NULL Byte of Longest IP Address String
77
Reserved
Reserved (Ethernet Message Type); must be 0
78–92
Reserved for Future Use
➀
The IP Address string format is up to 42 ASCII characters including a terminating NULL character. The first byte in the array is the
left-most character in the string as written. For example: If the IP Address is 423.156.78.012, the first byte is the ASCII character “4”. If
the MSG destination is an INTERCHANGE client on a host computer, the destination is specified as “client” and stored as a NULL
terminated string.