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Station ID
The Station ID is used to assign Setup, Read and Write blocks to a
particular server node. Station IDs range between 0 to 65535 and must be
unique in a model.
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Local IP Address
Enter the IP address of the Modbus server. This step does not assign
the IP address to an Ethernet interface. Instead, it binds the Setup
block to an IP address which was previously configured in the Ethernet
Configuration Tool. Refer to the Modbus usage notes
for further information.
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Local TCP Port
The TCP port the server listens on for connection requests from the
client. The default port is 502. For a custom port address, select
between the range 0 and 65535. The reserved ports should not be used.
Refer to the following online documentation:
List of TCP and UDP Port Numbers
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Units
Defines the IDs of the units the server node should manage in the
range of 0 to 255. Each unit has its own data tables for coils, discrete
inputs, holding registers and input registers. Modbus clients can
address a certain unit with the unit identifier in the Modbus request
frame. Typical Modbus servers that do not act as a Modbus RTU gateway
have only one unit.
According to the Modbus standard, unit ID 255 means NON-SIGNIFICANT.
If the unit identifier received is 255 but unit 255 is not configured in
the server, the requested command is performed on the first unit
specified in the Units parameter.
Default: [0] creates one unit with ID 0. Modbus requests with unit
identifier 0 or 255 are passed to unit 0.
Example: [0,255] creates two units with ID 0 and 255. Modbus requests
with unit identifier 0 are passed to unit 0. Modbus requests with unit
identifier 255 are passed to unit 255.
Example: [0,1,2,254] creates four units with ID 0, 1, 2 and 254.
Modbus requests with unit identifier 0 are passed to unit 0. Modbus
requests with unit identifier 1 are passed to unit 1. Modbus requests
with unit identifier 255 are passed to unit 0.
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Data Table Dimensions
Defines the number of coils, discrete inputs, holding registers and
input registers of each Modbus unit. The value must be an n-by-4 matrix
where n is the number of Modbus units. One row represents one unit, the
four columns represent the four Modbus data tables. The number of items
per data table must range between 1 and 65535.
Example: [1,2,3,4;5,6,7,8] The first unit has 1 coil, 2 discrete
inputs, 3 holding registers and 4 input registers. The second unit has 5
coils, 6 discrete inputs, 7 holding registers and 8 input
registers.
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Response Delay
Defines the number of milliseconds the server should delay a Modbus
response after having received a request. The number must range between
0 (no delay) and 60000.
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Swap Register Bytes
The bytes of a register must be swapped if the sender and the receiver
interpret the byte order in different ways (endianness). The Speedgoat
real-time target machine uses little-endian, while some clients use big-endian.
If the swap option is enabled, all register values from the
application context will be swapped before they are sent to the network.
All register values received from the network will be swapped before
they are submitted to the application context. The swap option only
affects input registers and holding registers (transmitted by function
codes FC3, FC4, FC5, FC6, FC16). Discrete inputs and coils are not
affected. Use Byte Reversal blocks instead of enabling the global byte
swapping if only single registers need to be swapped.
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Sample Time
Defines the base sample time at which this driver block gets its sample hit. This
parameter can also be set to -1 for inherited
sample time. The units are in seconds.