Modbus MFU Option Card Installation Manual
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Publication PUB091-003-00_0119
With a dual channel unit both channels user the same address. Changes to the register altering the
address will become effective only after the actuator power is cycled.
8.2.2
Baud Rate (Register 23)
Register 23 sets the communication baud rate. Note that the new setting for this register will not
become active until the actuator power is cycled. On a dual channel unit both channels operate at the
same baud rate.
8.2.3
Parity and Stop Bits (Register 24)
The parity and number of stop bits used in the communications is selected by altering the content of
this register. Note that the new settings for this register will not become active until the actuator power
is cycled. On a dual channel unit both channels operate using the same parity and stop bit setting.
8.2.4
Data Base Format (Register 25)
The Modbus Module can use different data base formats, the one to use is selected by the content of
this register. Note that the new settings for this register will not become active until the actuator power
is cycled. On a dual channel unit both channels operate using the same data base.
The Mk2 data base is as detailed in Section 7. Where the MFU is being used as a spare part to
replace the earlier design it is possible to select Mk1 data base where data and performance are as
the older unit. Appendix A gives the data base locations used by the Mk1 protocol.
8.2.5
Actuator Tag Name (Register 26 to 31)
The MFU may be programmed to contain a 12 character tag name string in these registers. Each byte
contains one character.
8.3 Return to Defaults
The card may be restored to the default settings for the configuration parameters, protocol and
address if necessary. To carry out this procedure will require the board to be fitted with a suitable
shorting link on LK1 (take care to select the link on the Interface Card and not the one on the NIC) and
the power to the card to be cycled. Note that the default data base format is Mk2.
Switch the actuator off
Access the Interface card and fit a shorting link across LK1
With the card in the actuator, switch the power on and off
Access the Interface card and remove the shorting link from LK1
The link LK1 must not be fitted under normal operating conditions.
This feature is not available for the ROMpak.
