User manual

Programmer’s Guide Page 58 of 66
E.g. when combining 3 DC270 4-channel digitizers, you would use channel number 10 in the function calls
config/get_MultiInput, config/get_Vertical and readData, if you wanted to refer to Input 2 of the third DC270.
Channel numbering does not depend on which module is the actual clock or trigger master.
3.18.2. Trigger Source Numbering with AS bus
Acqiris digitizers do not necessarily have as many internal triggers as channel inputs, nor exactly one external
trigger. You should retrieve, for every MultiInstrument, additional information with the following calls:
Acqrs_getInstrumentInfo(instrID, "NbrInternalTriggers", &nbrIntTrigs);
Acqrs_getInstrumentInfo(instrID, "NbrExternalTriggers", &nbrExtTrigs);
Acqrs_getInstrumentInfo(instrID, "NbrModulesInInstrument", &nbrModules);
nbrIntTrigsPerModule = nbrIntTrigs /nbrModules;
nbrExtTrigsPerModule = nbrExtTrigs /nbrModules;
In a MultiInstrument composed of 4 DC240 (2 channel, 2 GS/s digitizers), you would get 8 internal trigger sources, 4
external trigger sources and 4 for the value of nbrModules. Thus, nbrIntTrigsPerModule would be 2 and
nbrExtTrigsPerModule would be 1, as expected for a DC240.
Internal triggers are associated to the input channels, and follow the same numbering rules.
External triggers follow similar rules, i.e. extTrig = 1 corresponds to external trigger 1 of the first module, extTrig =
2 corresponds to external trigger 2 of the first module (if nbrExtTrigsPerModule > 1) or to external trigger 1 of the
second module etc. The externalTrigger 2 is the name used for the PXI Bus Star Trigger.
The functions AcqrsD1_configTrigSource and AcqrsD1_getTrigSource use the explicit trigger channel number,
with the internal trigger channel running from 1 to nbrIntTrigs, and the external trigger running from –1 to –
nbrExtTrigs. Note that 0 is an invalid trigger source, resulting in an error code.
The functions AcqrsD1_configTrigClass and AcqrsD1_getTrigClass encode the trigger source in a 32-bit source
pattern:
31
30
20 - 29
16 – 19
5 - 15
4
3
2
1
0
Ext 1
Ext 2
Other Ext Trigs
Module
Other Int Trigs
In 5
In 4
In 3
In 2
In 1
[0]
IN 1
Internal trigger channel 1
[1]
IN 2
Internal trigger channel 2
[2..4]
IN 3, IN 4, IN 5
Internal trigger channels 3, 4, 5
[5..15]
OTHER INT
TRIGS
Other internal trigger channels within a module, up to 16.
[16..19]
MODULE
Module Number, running from 0 to (nbrModules – 1).
In single digitizers, this field must be zero.
In MultiInstruments, the trigger source number must be broken into a
module number and a trigger channel number within the module.
[20..29]
OTHER EXT
TRIGS
Other external trigger channels within a module, up to 12.
[30]
EXT 2
External trigger channel 2
[31]
EXT 1
External trigger channel 1
In digitizers with trigger pattern capabilities, several trigger bits could be set simultaneously. However, no trigger
pattern capabilities between different modules can be coded, i.e. only a single module in a MultiInstrument can be the
trigger source, although the source in the single module might be a pattern. For these reasons, the module number
must be coded explicitly.
To translate a trigger channel number trigChan into a trigger source pattern, use the following code: