Operation
GA09420_002_C0 – (2016-10) –
Leybold
29
4.6 RS232C
Interface
The built-in RS232C interface allows transmission of digital measurement data and
instrument conditions as well as the setting of instrument parameters.
Caution
Caution: data transmission errors
If the transmitter is operated with the RS232C interface and a fieldbus
interface at the same time, data transmission errors may occur.
The transmitter must not be operated with the RS232C interface and
Profibus at the same time.
4.6.1 Description of the Functions
The interface works in duplex mode. A nine byte string is sent continuously without
a request approx. every 20 ms.
Commands are transmitted to the transmitter in a five byte input (receive) string.
Operational parameters
•
Data
rate
9600 Baud
set value, no handshake
•
Byte
8 data bits
1 stop bit
Electrical connections
•
TxD
Pin 13
•
RxD
Pin 14
•
GND
Pin 5
(Sensor cable connector)
4.6.1.1 Output String (Transmit
)
The complete output string (frame) is nine bytes (byte 0 … 8). The data string is
seven bytes (byte 1 … 7).
Format of the output string
Byte No Function
Value
Comment
0
Length of data string
7
(Set value)
1
Page number
5
(For ITR 90)
2 Status
→
Status byte
3 Error
→
Error byte
4
Measurement high byte
0 … 255
→
Calculation of pressure value
5
Measurement low byte
0 … 255
→
Calculation of pressure value
6
Software version
0 … 255
→
Software version
7
Sensor type
10
(For ITR 90)
8
Check sum
0 … 255
→
Synchronization
