Which wiring checks fix a sensor that will not report?
These are the electrical checks from the field handbook and the cabling guide, in the order they are normally run.
| Condition / fault | How to check | What to do |
|---|---|---|
| RS-485 A/B reversed | Check wire colours (A red / B white) | Swap A and B |
| RS-485 line broken | Continuity-test A/B with a multimeter | Re-terminate or replace the cable |
| Modbus address conflict | Check addresses on a multi-probe bus | Assign a unique address to each probe |
| Cable run up to 5 m | Standard probe cable length | Connect directly |
| Cable run 5–20 m | Use an extension of the same PUR shielded twisted-pair specification | Extend with matched cable |
| Cable run 20–100 m | Add an RS-485 repeater | Install the repeater on the bus |
| Cable run beyond 100 m | Not recommended on a long RS-485 run | Use a wireless sensor or place the controller nearby |
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Frequently asked questions
Do I need to register or leave an email to use these guides?
No. All troubleshooting and commissioning guides on this site are open pages with no form and no email gate. The full product datasheets are also open on the downloads page.
Do these pages publish spare-part prices or service fees?
No. These pages publish technical checks, wiring rules and procedures only. For spare parts, service terms or a quotation, contact [email protected].
What is the maximum RS-485 cable run in the guide?
Up to 5 m uses the standard probe cable, 5–20 m needs a matched PUR shielded twisted-pair extension, 20–100 m needs an RS-485 repeater, and beyond 100 m is not recommended.
Can several DO probes share one bus?
Yes. Give each probe a unique Modbus address; address conflicts are listed as a cause of abnormal readings and missing data.