7ML19985CL02 SITRANS LR 300 – INSTRUCTION MANUAL Page 91mmmmmTroubleshootingTroubleshootingCommunication TroubleshootingGenerally:1. Check the following:• There is power at the unit• The LCD shows the relevant data• The device can be programmed using the hand programmer2. Check the wiring pin-outs and verify that the connection is correct.3. Verify that values in set-up parameters P770 to P773 match the settings in thecomputer communicating with the unit.4. Check that the port you are using on the computer is correct. Sometimes trying adifferent Modbus driver will solve the problem. An easy stand-alone driver calledModScan32 is available from Win-Tech at www.win-tech.com. We have found thatthis driver is useful to test communications.Specifically:If you try to set an SITRANS LR 300 parameter via remote communications, but theparameter remains unchanged:• Some parameters can only be changed when the device is not scanning. Try puttingthe device in program mode using the operating mode function.• Try setting the parameter from the keypad. (First make sure that the lock parameter[P000] is set to 1954.)• The communications control parameter P799 must be set to 1 to be able to writeparameters to the SITRANS LR 300.
