How difference between modbus RTU and modbus ASCII
Modbus RTU to Modbus ASCII, but is a different question, or do the same. The difference is clear conclusion.
Different encryption methods by Modbus ASCII is ASCII code format, but that it is the Modbus RTU Bi Na Ry memory size is less data to be sent simultaneously to many Modbus RTU,
So surely that will be sent information. faster when large amounts of data.
The same principle is used for sending data is the same.
Table1. Modbus data structure
Both Modbus ASCII and Modbus RTU Address, but can identify different ASCII is a direct Hex base with two bytes when using Modbus RTU one byte.
Modbus serial links use two basic types of transmission, ASCII or RTU, remote terminal units. The mode of transmission of the serial communication defines how Modbus messages are encrypted. With Modbus / ASCII, all messages in an ASCII-readable format. The Modbus / RTU protocol uses binary format that makes the message unreadable, where the control, but reduces the size of each message that more exchange of information in the same time allows. All nodes on a Modbus network segment must use the same form of serial transmission. A device configured for Modbus / ASCII is not able to use the messages in Modbus / RTU understand and vice versa.
Table2. Properties for Modbus(ASCII) and Modbus(RTU)
When using Modbus / ASCII, all messages are encoded in hexadecimal values, represented in readable ASCII characters. Only the digits 0 … And 9 A. .. F are used to encode. For each byte of information, communications double-byte needed, because all communication is only 4-bit byte in the hexadecimal system defined. With Modbus / RTU data is exchanged in a binary format, where every byte of information is encoded in a single-byte communication.
Modbus messages over serial connections are not sent in a normal format. They are structured to give recipients an easy way to start and end of a message to find. When using Modbus / ASCII, the characters used to start and finish a frame. The colon ‘:’ is used to mark the start of a message and each message ends with a combination CR / LF. Modbus / RTU, using the other time gaps of silence on the line of communication for the definition. Each message should be preceded by a gap of time with a minimum length of 3.5 characters.
If a recipient of a hole at least 1.5 detects characters, it is assumed that a new message is received and the buffer is cleared. The main advantage of Modbus / ASCII, which differ between the bytes of a message allowes with a maximum length of 1 seconds. With Modbus / RTU is required for each post to send a continuous stream.
