IM 50.560CA UA (B/4-03) 61
DEPOLOX
®
3 PLUS RESIDUAL ANALYZER
3.7.4.2 Request - Frame
This is necessary to read data or additional information from a slave.
Format of the request frame:
Byte: 0-2 3 4 5 6 7 8 9
——————————————————————
Name: SYN SB SA ZA KB AB FC EB
Byte: Name: occupied by:
0-2 SYN Synchronization bytes
3 SB Start byte 10H
4 SA Slave address
5 ZA destination address
6 KB check byte
7 AB number of bytes
8 FC frame Check
9 EB end byte 16H
With the request frame, single words, values covering more addresses, or
additional information of the destination address can be read. If the contents
of a single destination address are requested, the number byte is set to 00Hex.
In the answer frame, the data format and the number of bytes are entered
from the address reference list to the check byte and the number byte.
If a number byte is set in the request frame (request covering more ad-
dresses), the data format in the answer frame is set to 04Hex (unsigned
char). The number byte of the answer frame receives the value of the
number byte of the request frame. A data format eventually entered in the
request frame is ignored.
If the additional information of a destination address is requested, the
check byte must include the identification for this additional information.
The data format and the number byte are ignored. The check byte and the
answer byte are set according to the reference list. Valid request frames
are answered with an answer frame. Invalid request frames are answered
with “negative confirmation.”
Example: Requesting the contents of destination address 02H from
slave 07H:
00H 00H 00H 10H 07H 02H 00H 00H 19H 16H
—————————————————————————
SYN SB SA ZA KB AB FC EB
To Next Page
Loading...