5
Creating Project Files—Modbus Master to Devices
44
Siemens Energy & Automation, Inc.
register 40001, etc. Be sure that the registers you
specified are not being used by other devices.
3.
Select
Save
to save the information to the project
file, and then select
Ok
or press
Esc
to exit the
device diagnostic registers screen. If at any time
you want to return to the last saved version of the
device diagnostics registers, select
Revert
with-
out saving any changes.
5.11
Device Command Registers
The device command registers consist of two consec-
utive registers for each device entered in the device
list. These registers allow the Modbus Master device
to transmit commands to each of the devices by writ-
ing to the appropriate register. The first register con-
tains the command, and the second register contains
the data associated with the command. The format of
the command registers for each device are described
in
Appendix E
.
All the command registers are placed in contiguous
locations and are assigned to each device in the order
that they are listed in the device list. To indicate the
location of the command registers, follow these steps:
1.
Select
Device Command Registers
from the
Edit
menu. The Device Command Registers screen
appears:
2.
Enter the starting register address in the
Modbus
Registers
field. The DTU3005 Editor software will
determine the proper number of registers for the
number of devices entered in the device list and
indicate the final register number. The registers
used are the holding registers (40000 to 49999).
Thus entering a register number of 1 will repre-
sent register 40001, etc. These registers must be
different from those used for device data and
diagnostics. Failure to use different register
addresses will cause communication errors, and
may cause unexpected operation of the devices.
3.
Select
Save
to save the information to the project
file, and then select
Ok
or press
Esc
to exit the
device command registers screen. If at any time
you want to return to the last saved version of the
device diagnostics register, select
Revert
without
saving any changes.
5.12
Saving the Project File
Now you have completed configuring the DTU3005 for
Modbus Master to Devices communications. Select
Save
from the
Project
menu and press
Enter
, or press
F10
to save the project file to disk. The next step is to
transfer the project to the DTU3005 unit. This topic is
covered in
Chapter 7
.
