---
title: If Rudolph Autopol external PC software shows Communication error during start up, these are the steps to troubleshoot.
description: If Rudolph Autopol external PC software shows Communication error during start up, these are the steps to troubleshoot.
---

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# If Rudolph Autopol external PC software shows Communication error during start up, these are the steps to troubleshoot.

## Steps for resolving Rudolph Autopol external PC software shows Communication error during start up, these are the steps to troubleshoot.

| Series 3 software Series 4 software |
| --- |
| Fix |
| In PC 1. Open Device Manager. 2. Expand ‘Ports (COM & LPT) 3. Note down the COM Port number of the USB-Serial adapter. 4. In the software, navigate to MENU/SETUP -\> CALIBRATION & SERVICE -\> INSTRUMENT SETTINGS -\> EXTERNAL CONTROL AND COM -\> VERSION. 5. Click FIRMWARE COMMUNICATIONS. 6. Make sure the COM port number is same as you noted down earlier. 7. Save and exit until the application closes. 8. Restart the application and check if the communication works. 9. If OK, exit troubleshooting. 10. Otherwise proceed to the instrument.   In Instrument 1. Click COMMUNICATION CONDITIONS button. Password is 519. 2. Set External control type to ‘None’. 3. Save and the instrument will restart. 4. After restart, check if the instrument boots to the user interface without any error. 5. See if the temperature or live reading is showing a valid value. If so, the instrument is working OK. 6. If not, let Rudolph know the problems observed. 7. If all is OK, set the instrument back to external control by clicking MENU/SETUP -\> CALIBRATION & SERVICE -\> INSTRUMENT SETTINGS -\> EXTERNAL CONTROL AND COM -\> EXTERNAL CONTROL. 8. Set External control type to ‘Rudolph External’. 9. Set COM port to 2 if the instrument has an Aaeon board or 3 if it is a Jetway board. 10. Save and the instrument will restart. 11. Start the PC software. |
| Applies to |
| Autopol External PC software - Series 2, Series 3, Series 4 |

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