Identify the Reported Condition
An NI 9870 installed in a cRIO 9012 chassis reported Error 65570 during a serial loopback test. The system used LabVIEW 8.5.1, NI-RIO 2.4, and Windows XP.
| Item | Evidence | Engineering decision |
|---|---|---|
| Error | 65570: serial module external power error | Inspect power at the module before troubleshooting serial data. |
| Required external power | 8–28 VDC at VSUP and COM | Confirm voltage and polarity directly at these terminals. |
| Measured supply | 16 VDC | The reported voltage is within the stated input range. |
| Initial test | RS-232 cable with a loopback connector | Do not treat one failed loopback accessory as proof of a failed module. |
Separate Power Evidence from Serial-Test Evidence
The measured 16 VDC at VSUP and COM satisfies the error message's stated 8–28 VDC requirement. That measurement does not, by itself, prove correct polarity, stable power under load, or a working serial path; it only confirms that the reported voltage falls within the specified range.
The available evidence does not establish why Error 65570 appeared despite the measured voltage. Keep the power indication and the failed loopback test as separate observations until each path is verified.
Test the NI 9870 Without the Suspect Loopback
- Measure the external supply directly across the NI 9870 VSUP and COM terminals and confirm it remains within 8–28 VDC.
- Inspect the RS-232 cable and loopback connector rather than assuming the NI 9870 has failed.
- Replace the single-port loopback test with a connection between two serial ports: transmit from one port and read the data on the other.
- Confirm that the received data matches the transmitted data. In the reported case, this test worked and identified the loopback connector as the suspected faulty component.
Determine Whether the Module Is Operational
The successful port-to-port transmit-and-receive test demonstrates that the tested NI 9870 serial path can move data. The evidence states that CompactRIO modules do not provide a self-test equivalent to the self-test available for NI DAQ devices in MAX, so module validation must use an application-level communication test.
Before connecting the intended SICK LMS 200, retain the known-good port-to-port test as a baseline. If that test passes but communication with the LMS 200 fails, move the investigation to the external device, cable, and serial communication settings; their required values are not supplied in the evidence.
FAQ
What does NI 9870 Error 65570 mean?
It reports that an external power error has occurred since the module was last accessed. Check for 8–28 VDC across the NI 9870 VSUP and COM terminals.
Can 16 VDC power an NI 9870?
Yes. The error text specifies an 8–28 VDC range, so a measured 16 VDC is within that range; also verify polarity and voltage at the module terminals.
How can I test an NI 9870 without a built-in self-test?
Connect two serial ports, transmit from one, and read from the other. Matching sent and received data validates the tested communication path and avoids relying on a potentially faulty loopback connector.