7-2
Section
Using Message Communications
95
The source words (starting with S) provide execution parameter and the com-
mand data as shown in the following table.
Word
Contents
S
Address of first word containing response
S+1
(See Specifying the Leading Address of the Response Words on page 95.)
S+2
Response monitoring time (hex)
0000:
2 s
1000 to 028F:
0.1 to 65.5 s (units of 0.1 s)
Above 028F:
65.5 s
S+3
Number of command bytes (hex)
0000 to 00F8: 0 to 248 bytes
S+4
.
.
.
Command data beginning with command code
The destination information provides the unit number of the destination Unit and
the number of words to be written, as shown in the following diagram.
D:
Digits 2 to 4: Number of words to write (001 to 128 BCD)
Digit 1: Unit number of the destination Unit (0 to F hex = 0 to 15)
Note
1. When sending explicit messages, set the response monitoring time in S+2
to 0014 Hex (2 seconds) or higher. If a shorter time is set, communications
may still be busy when the next command is sent after a timeout occurs.
2. The maximum number of bytes that can be transferred (shown above) is the
maximum number of bytes allowed with IOWR in C200HX/HG/HE PCs. The
actual number of bytes that can be sent or received depends upon the ex-
plicit message.
IOWR Data Area Ranges for C200HX/HG/HE PCs
The following tables shows the data areas that can be used for each parameter
of IOWR.
Area
C
S
D
Internal Relay Area 1
IR 000 to IR 235
Special Relay Area 1
SR 236 to SR 255
Special Relay Area 2
SR 256 to SR 299
Internal Relay Area 2
IR 300 to IR 511
Holding Relay Area
HR 00 to HR 99
Auxiliary Relay Area
AR 00 to AR 27
Link Relay Area
LR 00 to LR 63
Timer/Counter Area
TC 000 to TC 511
Data Memory Area
DM 0000 to DM 6599
Fixed DM Area
DM 6600 to DM 6655
Extended DM Area
EM 0000 to EM 6143
Constants
0000 to FFFF
Not usable
0001 to F128
Specifying the Leading Address of the Response Words
Specify the leading address as shown in the following table. These tables show
only the ranges that can be used with message communications (limited to ac-
cessing word units). Refer to the PC’s manuals for more details.
Word
Bits 00 to 07
Bits 08 to 15
S
Data area specifier
Leftmost 2 digits of address
S+1
Rightmost 2 digits of address
Bit (always 00)
