KNX/EIB Format ADCRead

[l0wside]

Der KNX-Standard definiert auf Layer 7 u.a. den ADCRead. Damit kann man u.a. die Busspannung am Gerät auslesen.

Hat jemand eine Übersicht, welche Werte (mit welchem Index) standardmäßig über dieses Interface ausgelesen werden können und wie diese kodiert sind? Ich weiß nur von "High Byte" und "Low Byte", kenne aber die Kodierung nicht - DPT9?

Max

[S. De Bruyne]

The A_ADC_Read-PDU shall contain the channel number of the AD-converter and the number of consecutive read operations to the AD-converter.

octet 6

octet 7

octet 8

APCI

read_count
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0

APCI
APCI APCI APCI
channel_nr
channel_nr channel_nr channel_nr channel_nr channel_nr







0
1
1
0















Figure 50 - A_ADC_Read-PDU (example)
The application process shall respond to the A_ADC_Read.ind primitive with an A_ADC_Read.res primitive containing the value of the AD-converter computed by the summation of the consecutive CPU accesses. If the remote application process has a problem, e.g. overflow when computing the summation, or wrong channel number, then the read_count of the A_ADC_Response-PDU shall be zero.

octet 6

octet 7

octet 8

octet 9

octet 10

APCI

read_count

sum

7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0










channel_nr








value high
value low

APCI
APCI APCI APCI










0
1
1
1
































And then a few documents further:
3.1.10.1 ADC Channels
The TP1 BCU1 shall allow a coarse estimation of the current bus via the AD-converter channel 1 and the A_ADC_Read-service. The value read can be converted to a voltage value by using the following formula:
Voltage = ADC_Value * 0,15V

It is however not required that this works! Don't be surprised to get 0 back.

[S. De Bruyne]

(tables do not seem to copy so well... :-(

[l0wside]

(tables do not seem to copy so well... :-(

No problem. "Voltage = ADC_Value * 0,15V" was the information I had been looking for.

Thank you.

Max