hi,
I knew the problem The problem was Visa laibrary is not installed
Question How to Write the address? as a string? how??
i need just write at least one command Correctly
Whoever command, reading and writing to gives command response thanks
in the modbus manual
Example 1 - Actual Data (3X References) To read actual parameters 2 and 3 (Current and Voltage, addressed as 1 and 2 hex) of the RVS-DN with a serial link number of 18, the host computer should send the following frame: byte 1: Serial Link No. ($18) byte 2: Function ($04) byte 3: Starting Address High ($00) byte 4: Starting Address Low ($01) byte 5: No. of Points High ($00) byte 6: No. of Points Low ($02) byte 7: CRC_Low ($XX) byte 8: CRC_High ($XX) The RVS-DN response, (when Current = 400 % of FLA, and Voltage = 420V) is: byte 1: Serial Link No. ($18) byte 2: Function ($04) byte 3: Byte Count ($04) byte 4: Data High, parameter 2 ($01) (400) byte 5: Data Low, parameter 2 ($90) byte 6: Data High, parameter 3 ($01) (420) byte 7: Data Low, parameter 3 ($A4) byte 8: CRC_Low ($XX) byte 9: CRC_High ($XX) Note: $XX indicates Hexadecimal byte.
Do you write the address as a string, such as 180400010002 first calculat crc and write crc low& high in the string
Is there a way to calculate the crc directly without the need for computed What are the functions necessary