User`s guide

Copyright © 2004 EIM COMPANY, INC. • 13840 PIKE ROAD • MISSOURI CITY, TX. 77489
Page 121
Controlinc 1746-C (Version 5.21) Network Master Users Guide (2004-11-18)
Example (in byte order) of a request to
preset register 40002 (internal holding
register 01) to 00 03 hex in slave device
17:
1. Slave Address 11
2. Function 06
3. Register Address Hi byte 00
4. Register Address Lo byte 01
5. Preset Data Hi byte 00
6. Preset Data Lo byte 03
7. CRC Hi byte ––
8. CRC Lo byte ––
6.5.2.4. Modbus Function Code 06 … Set Single Register
Using function code 06, the Modbus master (host) may directly address and write any Read/Write (RW)
memory register in the actuator. This includes registers that hold discrete values (inputs & coils).
Writing to a Read Only (RO) register will
• Have no affect on valve operation
• Be ignored by the application software.
• Cause the actuator to return a response indicating “illegal function code”.
Writing to a configuration data register that is Read/Write (RW) will cause the controller to compare the
written valve to the value stored in the EEPROM. If the value is different, the new value will be stored to
EEPROM configuration.
If a configuration coil is set which is dependent upon other configuration coils being set (and the other
coils are not set), a configuration error will be indicated that prevents valve actuator control.
Refer to the previous section that describes the “
Addressable Holding Registers”.
Response example (in byte order):
1. Slave Address 11
2. Function 06
3. Register Address Hi 00
4. Register Address Lo 01
5. Preset Data Hi 00
6. Preset Data Lo 03
7. CRC Hi byte ––
8. CRC Lo byte ––