3
Message structure
Generally, single data are transmitted, exceptions are shown in the
CODE-table (
Ä
chapter 4). Values in a reply are transmitted without
leading zeros, but minus sign/decimal point depending on the date.
Values in a transmission are valid within their limits with or without
decimal point. They will be cut and rounded to the required data
structure. Some parameters can be switched off by means of four minus
signs.
ADR
Address (2 bytes)
CODE
Code for data
VAL
Value of data
DATA
Comprises CODE = VAL
BCC
Block Check Count
Ü
CHR
Character
FCT
Function
*
Ü
All characters after STX and including ETX are connected bytewisely in an EXOR function (1 byte).
*
Function is the second part of the B2-codes. For B2,01 it is 01 and for B2,02 it is 02.
3.1
General structure
q
Computer requests:
EOT ADR ADR CODE CODE ENQ
With blocks B2, CODE and FCT must be requested:
CODE CODE , FCT FCT
General reply:
STX CODE CODE
=
t
VAL
r
ETX BCC
or
NAK
in case of error
Block 00 reply:
STX ST1 , ST2 , Y , W , X , Wv , Wnv , , HC/X2 ETX BCC
Blocks B2 reply:
CODE is B2. FCT is first part of VAL.
VAL
(Block B2,01):
0 1 , 1 0 , SP2 , SP3 , SP4 , SP5 , SP6 , SP7 , SP8 , SP9 , SP10 , SP11 , 0
VAL
(Block B2,02):
0 2 , 0 , 1 0 , Pt2 , Pt3 , Pt4 , Pt5 , Pt6 , Pt7 , Pt8 , Pt9 , Pt10 , Pt11
q
Computer transmits:
EOT ADR ADR STX CODE CODE
=
t
VAL
r
ETX BCC
With blocks B2, CODE and FCT must be transmitted:
CODE CODE , FCT FCT
FCT is repeated in VAL.
VAL
(Block B2,01):
0 1 , 1 0 , SP2 , SP3 , SP4 , SP5 , SP6 , SP7 , SP8 , SP9 , SP10 , SP11 , 0
VAL
(Block B2,02):
0 2 , 0 , 1 0 , Pt2 , Pt3 , Pt4 , Pt5 , Pt6 , Pt7 , Pt8 , Pt9 , Pt10 , Pt11
General reply:
ACK
or
NAK
in case of error
3.2
Messages ACK (write access) and NAK (write or read access)
The controller replies ACK to a write access, if all the following conditions are met:
w
Parity bit correct
w
Value is within its specified limits
w
BCC correct
w
Controller is at REMOTE mode
w
CODE permittted and positioned correctly
w
Permitted write access (e.g. Code 06)
w
Message contains only permitted characters
w
Message (data) received correctly
If one of the above conditions is not met, the controller replies NAK.
With message receive buffer overflow, the controller replies NAK.
With read access, remote or local operation does not affect the message.
3.3
Reaction times
The computer enquires for data (read access)
The computer sends data (write access)
w
The reply starts (STX) max. 150 ms after the
end of enquiry (ENQ).
w
The reply (ACK) starts max. 150 ms after the
end of transmission (BCC).
English
Message structure
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3
Interface description 9499 040 47701
