29
In order to allow the tool to access the Modbus devices, we must define a
DeviceNet parameter for each of the objects (secondary network Modbus
registers) that we wish to access. Let’s assume that the data shown in Table 3
is to be accessed on each of the respective Modbus devices, and that the
data’s characteristics are as indicated.
Table 3: Example Secondary-Network Data
Modbus Address
Modbus Register
Note
5
10
Frequency command (1=0.01Hz)
“
15
Operating frequency (1=0.01Hz)
“
120
Run/Stop command (run=0x0080)
“
125
Run/Stop status (running=0x0080)
7
2
Temperature sensor (1=0.1C)
“
4
Digital output (ON=0x0001)
9
8
Voltage monitor #1 (1=1v)
“
9
Voltage monitor #2 (1=1v)
“
10
Voltage monitor #3 (1=1v)
11
8
Voltage monitor #1 (1=1v)
“
9
Voltage monitor #2 (1=1v)
“
10
Voltage monitor #3 (1=1v)
From this table we notice that in total 12 DeviceNet parameters must be
created (one for each Modbus register to be accessed). By definition,
DeviceNet parameter numbers start at 1, sequentially increasing thereafter.
For the time being, we will ignore the additional gateway configuration required
to assign these parameters to be members of I/O assembly objects, and focus
simply on their existence and access via a configuration tool. Let’s begin by
creating our first DeviceNet parameter, which will map to Modbus register 10
(“frequency command”) on Modbus address 5. Via the DNET-100’s console,
we can add a new point, and configure it as follows:
DeviceNet parameter............................ 1 (automatically assigned)
Modbus RTU ID .................................... 5
Modbus RTU register number .............. 10
Name string .......................................... “Freq command”
Help string ............................................ “FC command value”
Units string............................................ “Hz”
Data Type ............................................. UINT
Read Only............................................. N
Max Value............................................. 8000
Min Value.............................................. 0
Default Enable ...................................... N
Default Value ........................................ 0
Allow Scaling ........................................ Y
Multiplier ............................................... 1
Divisor................................................... 100
Offset .................................................... 0
Precision............................................... 2
Summary of Contents for DNET-100
Page 8: ...7 2 Mechanical Diagrams 2 1 Enclosure Figure 2 Enclosure Dimensions units are inches ...
Page 9: ...8 2 2 Mounting Clip Figure 3 Mounting Clip Dimensions units are inches ...
Page 11: ...10 ASD Link LEDs Reserved LEDs ASD 2 ASD 3 ASD 1 Figure 6 Top View ...
Page 39: ...38 Figure 15 HyperTerminal Configuration Screen 3 ...
Page 68: ...67 16 Notes ...
Page 69: ...68 ...
