Hardware Manual COMBILOG 1020
130
11.8 MODBUS-Protocol
11.8.1
Transmission Sequence
The data are transmitted from and to the datalogger with follow-
ing sequence:
SD
..
..
ED
SD .. .. .. .. .. .. .. .. .. ED
request telegram
response telegram
T
1
request telegram
T
2
T
3
SD
..
..
ED
T1: time between two characters
T2: time between request-telegram corresponding response-telegram
T3: time between response-telegram and next request-telegram
Minimum and maximum appearing values for periods T1, T2 and
T3 and the adjustment ranges are given in table 11.14.
protocol baud rate T1 min T1 max T2 min T2 max T3 min T3 max
adjustable
no no yes no no yes
M
O
D
B
U
S
2400 bps
4800 bps
9600 bps
19200 bps
38400 bps
0
1,5 CT 3,5 CT
T2min
x
1.2
3,5 CT
0.1 to
600 sec
Table 11.14 Values and adjustment range for periods T1, T2 and T3
(CT: character time: 1 CT = character length [bit] / baud rate [bps])
Summary of Contents for COMBILOG 1020
Page 1: ...COMBILOG 1020 Datalogger Hardware Manual Version 3 09...
Page 2: ...Hardware Manual COMBILOG 1020 2 Issue 03 11 2005 Technical data are subject to change...
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Page 86: ...Hardware Manual COMBILOG 1020 86 Bild 8 1 Example Master Slave System...
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