Limitorque
®
Master StationI V EEP-SN4001 FCD LMENIM5010-00-AQ – 03/19
47
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7.2.5.3.4 Modbus FC 06/16 Preset Registers
Pressing the “Modbus FC 06/16 Preset Registers” button will take the user to the Modbus Holding Registers screen
for configuration of desired number of holding registers to be written per MOV. The 06 command presets a value into a
single-holding register, while the 16 command presets a value into a block of multiple holding registers. The data table
for these function codes permit either one or two write registers per field unit.
Figure 7.24 – Modbus holding registers – one per MOV shown
Selecting the “Next” button will advance the screen to a sample data table screen as shown below. Please note that a
unique table is created starting at register 45001. Specific field unit registry convention is as follows: DCS Command
Write Register = [(MOV address -1) * (selected number of registers per MOV)] + 45001. Address affect is accounted for
in the MSIV decoding process (i.e. 40,000).
Figure 7.25 – FC 06 sample data table with “Two Per Mov” selected
These function codes are typically used to command Limitorque Modbus field units by writing values directly into
command/argument registers. A predetermined value may be used to open/stop/close the actuator, move the actuator
to a preset position, activate/deactivate network ESD, reset the field unit, etc. See the following example of a request/
response exchange between the DCS and MSIV. Write register commands should be issued only once for the desired
field unit control. Repeated issuance of an acknowledged command will degrade network performance.
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