Emerson Rosemount 5300 Series - Page 187

7.6.1 Troubleshooting the HART
®
to Modbus
®
Converter
Table 7-18: Troubleshooting the HART to Modbus converter
Symptom Recommended actions
No communication on RS-485 bus (MA, MB) • Check that the cables are connected.
• Check that PWR+ is connected to + and PWR- is connected to - on the
power supply.
• Make sure the Rosemount 5300 Level Transmitter is supplied with
8-30 Vdc (max. rating).
• Try alternating MA/MB if you are unsure of the polarity.
• If an RS-485 converter is used, make sure it is properly installed and
configured.
• The last Rosemount 5300 Level Transmitter may need a terminating
120-Ω resistor connected between MA and MB.
No Rosemount 5300 communication in
Rosemount Radar Master
Using HART+, HART-:
• HART modem is not properly connected.
• Polling address is incorrect in Rosemount Radar Master (default 1).
Using MA, MB:
• See "No communication on RS-485 bus".
• Polling address is incorrect in Rosemount Radar Master (default 1).
• Cycle the power and wait 20 seconds before polling.
No communication with Modbus RTU
protocol
• See "No communication on RS-485 bus".
• Make sure the “Modbus communication protocol configuration” is
done properly, see Modbus communication protocol configuration.
• Make sure the Modbus RTU address is unique on the bus.
• Cycle the power and try to connect.
• Check the RTU communication settings.
No communication with Modbus ASCII
protocol
• See "No communication on RS-485 bus".
• Make sure the “Modbus communication protocol configuration” is
done properly, see Modbus communication protocol configuration.
• Make sure the Modbus ASCII address is unique on the bus.
• Cycle the power, waiting 40 seconds before communication begins.
• Check the RTU communication settings.
Reference Manual Service and troubleshooting
00809-0100-4530 April 2019
Reference Manual 187