2
Interface protocol
The protocol is based on ISO 1745. Generally, a fixed master/slave principle is used for transmission,
whereby the controller is always the slave. Control is always by the master.
Two data transmission services are available:
q
Send Data with Acknowledge SDA (Data transmission with acknowledgement by the controller)
q
Request Data with Reply RDR (Data request with reply by the controller)
2.1
Data format
w
1 start bit
w
1 parity bit (EVEN)
w
7 bit binary (status byte) or
7 bit ASCII (other data)
w
1 stop bit
2.2
Baud rate
The Baud rate of 2400/4800/9600/19200 Bd is adjustable at the configuration level.
The same Baud rate must be adjusted on all instruments which are connected to the interface module.
2.3
Adress setting
The controller can be operated at the same bus with other instruments and systems. Decisive for
instrument selection is the address
Adr
=
00
...
99
(parameter level).
2.4
Characters
Transmission control characters
Valid 7-bit-characters (parity EVEN):
CHR HEX Description
CHR HEX Description
STX
02
Start of data
,
2C
Comma as separation
ETX
03
End of data
=
3D
Separation for CODE = VAL
EOT
04
Reset or cancellation
.
2E
Decimal point (only for VAL)
ENQ
05
Enquiry of reply
-
2D
Minus (only for VAL)
ACK
06
Acknowledge
0...9
30...39
Numbers 0...9
NAK
15
Not Acknowledge
@...
40...7F
Values of the status bytes
+
The characters for "space"and "+" (hex 20, 2B) are inadmissible in all messages.
Interface protocol
English
Interface description 9499 040 47701
2
960612
