Thommen HM28 - RS 232 Communication; RS 232 Mode Operation; RS 232 Pin Assignment; RS 232 Protocol and Commands

17
e
Code Configuration
Pressure unitPressure unit
Pressure unitPressure 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
ResolutionResolution
ResolutionResolution
Resolution
0 low
1 high
DampingDamping
DampingDamping
Damping
0on
1 off
BaudrateBaudrate
BaudrateBaudrate
Baudrate
0 1200 Baud
1 2400 Baud
2 4800 Baud
3 9600 Baud
Code Configuration
Cut-out timeCut-out time
Cut-out timeCut-out time
Cut-out time
0 60 min
1 continous
2 1 min
3 10 min
Time unitTime unit
Time unitTime unit
Time unit
0 /hours
1 /minutes
Storage intervalStorage interval
Storage intervalStorage 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 rateDisplay rate
Display rateDisplay 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»