Setting intf.src_term_start_trigger results in error with cDAQ & NI9862 #299
Description
I was/am unable to set the source terminal start trigger for any interface session. This is useful for syncing between DAQmx and XNET. This is using a cDAQ-9189 with an NI-9862 XNET module.
Steps Involved:
Create any input or output session and try to set the intf.src_term_start_trigger. I received the following error:
nixnet.errors.XnetError: NI-XNET: (Hex 0xBFF630C0) A property value was out of range or incorrect. Solution: Specify a correct value.
I checked the output in NI IO Trace, and saw that when the value was read using nxGetProperty, the length was 1 more than the number of characters. For example:
nxGetProperty (0x00400001, "nxPropSession_IntfSrcTermStartTrigger", 32 (0x20), "/cDAQ9189-xxxxxxx/Slot6/Convert")
"/cDAQ9189-xxxxxxx/Slot6/Convert" has 31 characters, but a length of 32. It seems XNET wants the length+1 for the string. This is not followed when setting the property. The command to set the property:
nxSetProperty (0x00400001, "nxPropSession_IntfSrcTermStartTrigger", 33 (0x21), "/cDAQ9189-xxxxxxx/ai/StartTrigger")
Has 33 characters for the trigger source, and a length of 33. This was returning the error above.
I modified _cprops.py, line 204 from:
value_size = len(value_bytes) * _ctypedefs.char.BYTES
to:
value_size = len(value_bytes) * _ctypedefs.char.BYTES + 1
And that solved the problem. I was able to set the start trigger.
- OS: Windows 10.0.19044
- Python version: 3.9
- NI-XNET version: 2023 Q4
Installed packages and version
| Package | Version |
|---|---|
| blosc2 | 2.2.9 |
| contourpy | 1.1.1 |
| cycler | 0.12.1 |
| deprecation | 2.1.0 |
| et-xmlfile | 1.1.0 |
| fonttools | 4.43.1 |
| importlib-resources | 6.1.0 |
| kiwisolver | 1.4.5 |
| matplotlib | 3.8.0 |
| msgpack | 1.0.7 |
| ndindex | 1.7 |
| nidaqmx | 0.8.0 |
| nixnet | 0.3.2 |
| npTDMS | 1.7.1 |
| numexpr | 2.8.7 |
| numpy | 1.26.1 |
| openpyxl | 3.1.2 |
| packaging | 23.2 |
| pandas | 2.1.2 |
| Pillow | 10.1.0 |
| pip | 22.3.1 |
| py-cpuinfo | 9.0.0 |
| pyparsing | 3.1.1 |
| python-dateutil | 2.8.2 |
| pytz | 2023.3.post1 |
| scipy | 1.11.3 |
| setuptools | 65.5.1 |
| six | 1.16.0 |
| tables | 3.9.1 |
| tzdata | 2023.3 |
| wheel | 0.38.4 |
| zipp | 3.17.0 |