ABB 266 MODBUS - 6.3 Communication failure

6 Troubleshooting
76 | 266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB
Communication failure
There are two approaches for troubleshooting communication. First, verify that the communication parameters in the transmitter
have been properly set. Second, verify that the RS-485 MODBUS
®
communication connection (Bus + and Bus -) is correctly
wired and properly terminated. Use the following procedures to troubleshoot a communication failure.
Verifying communication parameters
Communication setup parameters must match the settings in the Host device for proper communication.
1. Press the right soft key to access the HMI Main Menu.
2. Use the key pad to locate and select Communication.
3. Scroll through the communication menu and verify that all the parameters for this transmitter match those set in the Host
device (Table 17).
Table 17: Communication parameters
Main Menu
Submenu 1
Selections
Communication
TAG
(enter name)
Address
Modbus address 1-247
Baud rate
1200
2400
4800
9600
19200
38400
Response Delay
(in ms)
Parity
None
Even
Odd
Modbus Map Select
ABB 266\x2F267 Map
Rosemount 3095FB Map
Invensys IMV25 Map
Modbus Reg. Offset
Zero Based
One Based
a. If the parameters do not match those set in the Host device, make adjustments.
b. If an adjustment was made to the parameters and the communication has been restored, it is not necessary to
continue this procedure.
c. Exit the menu when finished.
4. If there are multiple transmitters on the bus, verify that all parameters for each transmitter match those set in the Host
device.
a. If the parameters do not match those set in the Host device, make adjustments.
b. If an adjustment was made to the parameters and the communication has been restored, it is not necessary to
continue this procedure.
5. If communication has not been restored, proceed to section 6.3.2, RS-485 wiring connections.