Operating Manual CHM 8k
R1.7 / 01-2020
Communication via RS485 & Ethernet
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The value 2A is the checksum of the response line.
8.2.3 Changing the baud rate
The option to change the baud rate is a specific feature. The change takes place as described in 8.2.2
Setting a parameter. Thus, baud rate no. 4 that corresponds to 19,200 bits/s, is set with
set<SPACE><RNO>:Baud=4<CR><LF>
The correlation between baud rate # and baud rate is shown in Table 6
Baud rate #
Baud rate [bit/s]
(0)
(1,200)
(1)
(2,400)
2
4,800
3
9,600
4
19,200
5
38,400
6
57,600
7
115,200
Table 6 Correlation between baud rate # and baud rate.
Baud rates 0 and 1 are not specified within the time limit. After sending a set command, the interface is
immediately set to the new baud rate. An incorrectly set baud rate will lead to transmission errors
afterwards and would make a normal reset impossible because of the lack of communication capability.
After expiry of the time interval specified in TimeOutRS485 (default value: 30 s), the incorrect baud rate
is reset to the baud rate defined in the parameter BaudAfterError. This guarantees that the user can
regain control of the device after this waiting period. The default value of BaudAfterError is 3, which
corresponds to 9,600 bits / second. The default value should be modified by the user, too, in case a baud
rate of e.g. 19,200 is always used.
8.2.4 Restarting the embedded Linux system / factory settings
The command
set<SPACE><RS485Number>:Reset=1<CR><LF>
instructs the internal processor to perform an immediate restart. This restart takes less than one minute.
Communication with the CHM 8k is not possible during this time; any current automatic telegram output
is also interrupted.
The command
set<SPACE><RS485Number>:ResetSettings=1<CR><LF>
resets all parameters to the factory settings.
The command RSN restarts the network. A restart is always necessary if the network settings, e.g. IP
address, DHCP mode, etc., have been changed. The new network settings are only used after entering
the commands RSN or RST.
set<SPACE><RS485Number>:RSN=1<CR><LF>
8.2.5 Changing the time settings
set<SPACE><RS485Number>:dts=30<CR><LF>