RHEONIK Messgeräte GmbH
REV. I, Apr. 2004
.
Operation Manual RHE 07, 08, 11
Page
20
2.1.3.6.2. Serial communication
The RHE remote electronic unit supports either
RS422 / 485 full duplex
(4 wire system) interface
(RS232 only as special option).
TTL level serial can also be used. Transmission baudrate can be set in baudrate menu (300, 600,
1200, 2400, 4800, 9600, 19200 bits/second).
The serial interface can be used in a bus (4 wire). For this purpose each remote unite has to be
addressed separately.
For RS422/485 connect communications wiring pairs to the TX+/TX- terminals and to the RX+ /RX-
terminals (see attached wiring diagram).
Standard character format is:
7 bit ASCII, 1 start bit, 1 stop bit, parity bit EVEN.
For network communication each transmitter RHE has to have its own
network address from A to Z
available in menu
Setup I/O
/
Dig
in menu point
Network Adr
.
Basic Command Format:
Commands are sent by the computer to the transmitter. The message protocol uses only ASCII char-
acters as follows:
- Command header:
<7FH><7FH><#>[<address>]
Address is any character
´
A
´
to
´
Z
´
. If the transmitter has no address, no address character needs to
be transmitted. If
´$´
is transmitted as an address, this character is valid as an address. All transmit-
ters in a network will respond to this signal.
- Request instructions:
If any of the below listed request instructions are transmitted after the command head, the transmit-
ter will send back the requested information.
request for
command
RHE reply
example
flow rate
f?
f= ...
f=_1.987kg/min
totalizer
q? q=
...
q=____413.4lb
temperature
t? t=
...
t=-_12.4C
density*)
d? d=
...
d=16.435lb/gal
totalizer
(non resetable)
m? m=
...
m=___36782kg
analog input
a? a=
...
a=_10.16bar
error message **)
e? e=
...
e=3FH
warning **)
w?
w= ...
w=5
*) Only with option density measurement.
**) error and warning code in HEX
