Solution
It is not possible to use the
NI-9871 to communicate directly with an RS-232 device. The module is equipped with RS-485/422 transceivers designed to meet the ANSI/EIA/TIA-485 standard, which specifies the electrical and functional specifications for a balanced voltage digital signaling system that uses a differential signal for transmission in a multi-drop network. On the other hand, RS-232 uses single-ended signals, which are different from the differential signals used in RS-485/422.
If necessary, a third-party RS-485 to RS-232 converter can be used to connect the NI-9871 to an RS-232 device. However, NI offers another module, the
NI-9870, equipped with RS-232 transceivers and fully compatible with the ANSI/EIA/TIA-232 standard.
Using a NI-9870 module for RS-232 communication instead of the RS-485 to RS-232 converter with the NI-9871 ensures that the correct transceivers are used for each type of communication, ensuring maximum compatibility and reliability.
The above behavior and recommendations also apply when trying to communicate with an RS-485/422 device using an RS-232 module, like the NI-9870.