X20 system modules • Analog input modules • X20AI1744, X20AI1744-3
X20 system User's Manual 3.10
139
Synchronous mode
Beginning with firmware version 2, the analog/digital converter (ADC) on the X20AI1744 module can be operated
and read synchronously with the X2X Link. Synchronous mode is activated by selecting the respective operating
mode in the
ADC configuration
register. A time between 200 and 2,000 µs must also be set in the
ADC cycle time
register. If this time is a whole number factor or multiple of the configured cycle time of the X2X Link, then the ADC
is synchronously read with the X2X Link.
Information:
The ADC cycle time must be ≥1/4 of the X2X cycle time.
The bit 2 in
Module Status
is set (i.e. ADC does not run synchronously), ...
•
... if the configured ADC cycle time cannot be synchronized with the X2X Link.
•
... if the module is still in the settling phase.
Jitter, dead time and settling time:
Jitter
ADC cycle times <1500 μs
ADC cycle times >1500 μs
Max. ±1 μs
Max. ±4 μs
Dead time on the X2X Link
50 μs +
X2X cycle time
128
Settling time
Firmware Version ≤
Firmware Version ≥5
Max. 150 x ADC cycle time
150 x X2X cycle time
Table 24: Jitter, dead time and settling time
The settling time corresponds to the time needed until the AD converter can be operated after activating the syn-
chronous mode or following conversion of the ADC cycle time.
4.3.2.11.4.4 ADC cycle time
Name:
ConfigCycletime01
This register is only used in "Synchronous mode". If synchronous mode is enabled in the ADC configuration, then
the module attempts to operate the ADC synchronously to the X2X Link (based on the ADC cycle time specified
in this register). It is necessary for the X2X Link cycle time and the ADC cycle time to have a certain relationship.
The following conditions must be adhered to:
1 ADC cycle time ≥ 1/4 X2X cycle time
2 ADC cycle time corresponds to a whole number factor or multiple of the X2X cycle time
3 ADC cycle time must be in the range from 50 to 2000 µs
Data type
Value
UINT
50 to 2000
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