17
e
Code Configuration
Pressure unit
Pressure unit
Pressure unit
Pressure unit
Pressure unit
5
MPa(7-70bar)
6
Pa(25mbar-7bar)
7
kPa
8
bar
9
mH2O(with 70bar,
otherwise mmH2O)
10
mmHg(not with
70bar)
11 psi
12
inH2O
13
inHg (not with
70bar)
14
hPa
15
mbar
Resolution
Resolution
Resolution
Resolution
Resolution
0
low
1
high
Damping
Damping
Damping
Damping
Damping
0
on
1
off
Baudrate
Baudrate
Baudrate
Baudrate
Baudrate
0
1200 Baud
1
2400 Baud
2
4800 Baud
3
9600 Baud
Code Configuration
Cut-out time
Cut-out time
Cut-out time
Cut-out time
Cut-out time
0
60 min
1
continous
2
1 min
3
10 min
Time unit
Time unit
Time unit
Time unit
Time unit
0
/hours
1
/minutes
Storage interval
Storage interval
Storage interval
Storage interval
Storage interval
2
10 s
3
20 s
4
30 s
5
60 s
6
2 min
7
3 min
8
5 min
9
10 min
10
30 min
11
60 min
12
manual
13
off
14
1 s
15
5 s
Display rate
Display rate
Display rate
Display rate
Display rate
0
5 Hz
1
2.5 Hz
Reply to control command
«
readconfig
»
A whole number is returned as a reply
msb
lsb
#### #### #### ####
|||| |||| |||| ****-
Pressure unit
|||| |||| |||*------
Resolution
|||| |||| ||*-------
Damping
|||| |||| **-------- Baudrate
|||| ||**-----------
Cut-out time
|||| |*-------------
Time unit
|***-*--------------
Storage interv
*-------------------
Display rate
3.5
RS 232 mode
The HM28 can be remotely operated from a
personal computer via an RS 232 interface.
The automatic cut-out (chapter 3.1) is
inoperative. Connection by means of a RS232-
cable.
Plug pin assignment RS 232, DB 9 (female)
Pin
Assignment
Pin
Assignment
1
DCD
6
DSR
2
TXD
7
RTS
3
RXD
8
CTS
4
DTR
9
SHIELD
5
GND
Protocol
ASCII-commands
9600/4800/2400/1200 baud, 8 bit, no parity,
1 stop bit,
XON/XOFF - protocol (17 dec/19 dec)
Notes
- The HM28 is switched on when the
supply voltage is applied
- The HM28 sends "XON" every 3 seconds
To determine the baud rate, read-in
"XON" in each transfer rate until "XON"
is correctly identified
- To go to remote control mode, interrogate
"XON", immediately send the "remote"
command and then read-in the
acknowledgement "ok"
- Only lower case letters are accepted
- Observe > 0,1 s delay before the next
command after "setbaud" command
- To acknowledge the answer of the HM28
without reading it back, just send a "XON"
- The symbol "*" followed by the checksum
must be suffixed to each string. The string
must be terminated with a CR
- A "TAB" is prefixed to each checkback
signal of the HM28, a "*" suffixed and the
checksum sent. The checkback signal is
terminated with a CR
- The checksum is formed from the lowest-
order byte of the command string
Code-decoding of control command
«
readconfig
»
Summary of Contents for HM28
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