Trouble with RS485 Communications?
Here are some tips on connecting LVT units using RS485 cables.
- Try to arrange a local RS485 connection from your PC. Bring the LVT modules one-by-one to this local connection.
- Use the VT Setup software to change the address of each LVT module in turn. LVT modules are sent out with default address 0. If you connect the LVT to your RS485 link, and power up the LVT, VT Setup should find it at address 0. You will need each LVT on an RS485 connection to have a different address. Start from 1 and work up. It is best to leave address 0 free so that you can add a new LVT to your system and find it while all the others remain connected.
- If you do not arrange a local connection, check each LVT in turn. That is, go to the nearest LVT to the PC with only a single section of cable between the PC and LVT, and disconnect the rest of the LVTs.
- Check the continuity of the cable by twisting the Tx+ and Tx–, and the Rx+ and Rx– wires at one end of the cable section and using a multimeter to check continuity at the other. You can then check continuity of a new length of RS485 cable and attach it to the 5-way screw terminal block.
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RS485 cable should be 2 twisted pairs + screen. Use:
1 pair for Tx pair
1 pair for Rx pair
and screen for signal ground.
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