ALTUS Nexto NX3004 - Page 114

4. Configuration
106
Variable
or GVL
Disabling Variable
Variable used to disable
MODBUS
-
Field for symbolic variable used to disable
MODBUS requests individually configured.
This variable must be of BOOL type. The
variable can be simple or array element
and can be in structures.
Table 4-71. MODBUS Client Relations Configuration
Notes:
MODBUS Relation Settings: the number of factory default settings, and the values for the column
Options, may vary according to the data type and MODBUS function (FC).
Function Code: MODBUS functions (FC) available are as follows:
Function Type
Code
Description
DEC
HEX
Access to Variables
1
0x01
Read coils (FC 01)
2
0x02
Read input status (FC 02)
3
0x03
Read holding registers (FC 03)
4
0x04
Read input registers (FC 04)
5
0x05
Write a coil (05 FC)
6
0x06
Write a holding register (FC 06)
15
0x0F
Write multiple coils (FC 15)
16
0x10
Write holding registers (FC 16)
22
0x16
Register write mask (FC 22)
23
0x17
Read/Write holding registers (FC 23)
Table 4-72. MODBUS Client Functions
Polling: this parameter indicates how often the communication set for this request must be
performed. By the end of a communication will be awaited a time equal to the value configured in
the field scan and after that, a new communication will be executed.
Read Data Start Address: field for the initial address of the MODBUS read data.
Read Data Size: the minimum value for the read data size is 1 and the maximum value depends on
the MODBUS function (FC) used, as below:
 Read Coils (HR 1): 2000
 Read Input Status (FC 2): 2000
 Read Holding Registers (HR 3): 125
 Read Input Registers (HR 4): 125
 Read/Write Holding Registers (FC 23): 121
Read Data Range: this field shows the MODBUS read data range configured for each request. The
initial address plus the read data size will result in the range of read data for each request.
Write Data Start Address: field for the initial address of MODBUS write data.
Write Data Size: the minimum value for the size of the write data is 1 and the maximum value
depends on the MODBUS function (FC) used, as below:
 Write Coil (HR 5): 1
 Write Holding Registers (FC 6): 1
 Write Multiple Coils (FC 15): 1968
 Write Holding Registers (FC 16): 123
 Register write mask (FC 22):
 Read/Write Holding Registers (FC 23): 121