Gantner IDL 101 - ASCII-Protocol

IDL 101
COMMUNICATION
62
HB_IDL101_E_V222.doc
Gantner Instruments Test & Measurement GmbH
10.2. ASCII-Protocol
10.2.1. Transmission Sequence
In the ASCII-protocol data are transmitted from and to the data logger by means of the following sequence:
SD
.. ..
ED SD .. .. .. .. .. .. .. .. .. ED
request telegram response telegram
T
1
request telegram
T
2 T3
SD
.. ..
ED
T
1
: time between two characters
T
2
: time between request-telegram and corresponding response-telegram
T
3
: time between response-telegram and next request-telegram
You will find the minimum and maximum appearing values for T
1
, T
2
and T
3
and the adjustment range in the following
table 10.7.
protocol baud rate T
1min
T
1max
T
2min
T
2max
T
3min
T
3max
adjustable no no yes no no no
A
S
C
I
I
2,400 bps
4,800 bps
9,600 bps
19,200 bps
38,400 bps
0 arbitrary 1..80 ms 80 ms 3 CT arbitrary
Table 10.7 Values and adjustment range for the times T
1
, T
2
and T
3
(CT: character time: 1 CT = character length [bit] / baud rate [bps])
Notice : In the ASCII-protocol T
2max
amounts at least 80 msec.
The values for T
2min
and T
3max
and the behavior of the data logger if the time T
3max
is exceeded (communication timeout,
see also chapter 6.8, error handling) can be adjusted by means of the
Configuration Software ICP 100 . The default
values for the time T
2min
is 1 CT and for the time T
3max
60 sec.
10.2.2. Telegram Format
For the request and response telegram it is distinguished between telegrams without and with check sum in the ASCII-
protocol. The various telegrams are differentiated by varying Start-Delimiters (SD). A request telegram without check
sum will lead to a response telegram which will also contain no check sum. The corresponding is valid for requests with
check sum. Furthermore there are two short telegrams with a length of one character each. With these telegrams a
positive or negative acknowledge respectively can be performed.