Woodward highprotec MRI4, User Manual

Page: 191 / 727

Communication Protocols
Modbus RTU
Part 1: Configuration of the Devices
Call up
»Device parameter/Modbus« and set the following communication parameters there:
Slave-address, to allow clear identification of the device.
Baud-Rate
Also, select below indicated RS485 interface-related parameters from there, such as:
Number of data bits
One of the following supported communication variants: Number of data bits, even, odd, parity or no parity,
number of stop bits.
»t-timeout«: communication errors are only identified after expiry of a supervision time »t-timeout«.
Response time (defining the period within which an enquiry from the master has to be answered).
Part 2: Hardware Connection
For hardware connection to the control system, there is an RS485 interface at the rear side of the device
(RS485, fiber optic or terminals).
Connect bus and device (wiring).
Error Handling - Hardware Errors
Information on physical communication errors, such as:
Baudrate Error
Parity Error ...
can be obtained from the event recorder.
Error Handling – Errors on protocol level
If, for example, an invalid memory address is enquired, error codes will be returned by the device that need to be
interpreted.
191 MRI4 DOK-HB-MRI4-2E