4. Configuration
106
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:
Read input status (FC 02)
Read holding registers (FC 03)
Read input registers (FC 04)
Write a holding register (FC 06)
Write multiple coils (FC 15)
Write holding registers (FC 16)
Register write mask (FC 22)
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:
ï‚· Read Coils (HR 1): 2000
ï‚· Read Input Status (FC 2): 2000
ï‚· Read Holding Registers (HR 3): 125
ï‚· Read Input Registers (HR 4): 125
ï‚· 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:
ï‚· Write Coil (HR 5): 1
ï‚· Write Holding Registers (FC 6): 1
ï‚· Write Multiple Coils (FC 15): 1968
ï‚· Write Holding Registers (FC 16): 123
ï‚· Register write mask (FC 22):
ï‚· Read/Write Holding Registers (FC 23): 121