Yokogawa HART Communicator YHC5150X - Manual (Page 39)

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The user now has the option of making further modifications to the parameters on the HART
®
menu, or
committing them to the device.
4.7 Communication Troubleshooting
If a HART
® device is connected to the unit but “No Devices Found” notification is received, or the device is
not in the table of found devices:
1) Make sure all connections are correct and secure. Check for shorts, open circuits and multiple
grounds.
2) Determine if the loop resistance is greater than 250
Ω and less than 1100Ωs. If less than 250 Ω
then use the supplied 250
Ω load resistor in series with the loop (see diagram HART ® Connections
section).
3) Determine if any device is in burst mode. Disable burst mode if possible during troubleshooting.
4) Check the polling address type and range selected from the system menus. If the polling address
set on the transmitter is outside of the range selected for the communicator, the device will not be
discovered. Set the poll type to “by address” and set the polling address range to the maximum (0-
15 for HART
® Universal Revision 5 devices, 0-63 for newer HART ® devices). Start a new poll
and determine if the device is found.
5) If multiple HART
®
devices are in the loop, there could be an address conflict (two devices at
same address). Testing the devices individually is the best path.
6) Determine if there are multiple master devices on the loop. HART
® communication only permits
one primary and one secondary master. Remove all other master devices from the loop for
troubleshooting.
When the message “Generic” is displayed after connecting to a HART
® device there are two possible causes:
1) No device specific DD for that device is currently installed in communicator memory. This
could occur if the device DD has not been released by the HART Communication Foundation
(visit their website for full list), or if the DD database on your PC requires updates. See section
5 for update instructions. The connected HART
® device supports only HART ® Universal and
Common Practice commands (i.e. generic commands). There are several such devices on the
market, particularly level type devices.
If multiple devices of the same name appear at different addresses, the cause is normally a HART
®
Universal Revision 5 device in the loop and the polling range selected on the communicator extending
beyond HART
® polling address 15. Addresses beyond 15 were undefined until HART ® Universal
Revision 6.