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VACON® 1000 Fieldbus Options
Operating Guide
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When a new frame of data is started, the transaction ID increases by 1.
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Serial input data length: Select "Close" in input data length when configuring fieldbus part in software. The data length is not
shown in the DP input area. Instead, it shows transaction plus data. Select "Open" and DP input area shows data length.
Example
If PROFIBUS input byte selected is 8 bytes input, serial input data length is 3, data is 04 05 06, and the current transaction ID is 0.
Input data format: [01] [03] [04] [05] [06] [00] [00] [00]
4.7.4 Frame Type
Frame type is used for the PROFIBUS DP module to define the end of a data frame sent from a user serial device.
Frame type includes:
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Time interval between characters
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Frame length
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Delimiter
4.7.4.1 Time Interval Between Characters
When a serial device sends data to the PROFIBUS DP module, the module starts timing for every byte that the serial device sends
out. If the arrival time of the next byte exceeds the set time interval (timeout time), the PROFIBUS DP module considers the previous
received N continuous bytes as a data frame. Then, it combines this N or N-2 bytes into one "PROFIBUS input data frame" and sends
it to the PROFIBUS master. If "Use CRC check" is selected, the PROFIBUS DP module executes a CRC check of the former N-2 bytes:
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If the check is correct, data is sent to the PROFIBUS master.
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If the check is incorrect, this data frame is discarded.
For example, time interval between characters is set to 10 ms, no CRC check, input and output bytes length of PROFIBUS master is 8
bytes. The serial device first sends out byte 0x11. After the PROFIBUS DP module receives 0x11, it starts the character interval timer.
If the PROFIBUS DP module receives the next byte within 10 ms, it restarts the character interval timer. Otherwise, it considers re-
ceiving one complete data frame. The data word is all HEX.
The data length that the PROFIBUS DP module sends to the serial device depends on the data value in the frame that PROFIBUS
sends to the PROFIBUS DP module.
4.7.4.2 Frame Length
This frame type is suitable for receiving serial data frame of specific length. When receiving bytes from serial devices, the PROFIBUS
DP module automatically launches the time interval between characters function. Under the following two conditions, the PROFI-
BUS DP module considers that it has received one frame data:
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The adjacent bytes received from user serial devices do not time out; the receiving bytes number is equal to "frame length". Or,
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The bytes received from the serial device characters times out.
When the PROFIBUS DP module has received one frame data, it disposes of this frame if data numbers equal to the set frame length.
Otherwise, discard the frame directly. If selecting "Use CRC Check", it does the CRC check first and discards the frames that did not
pass the CRC check.
For example, set frame type to "Frame length", the length of characters is 4 bytes, time interval between characters is 10 ms, no CRC
check, and input and output bytes length of PROFIBUS master is 8 bytes. If receiving 4 bytes continuously with no characters time-
out, the PROFIBUS DP module packages this frame data into one "PROFIBUS input data" frame and sends it to PROFIBUS master. If
characters time out, it directly discards the data less than 4 bytes. The data are HEX.
The data length that the PROFIBUS DP module sends to the serial device depends on the data value in the frame that PROFIBUS
sends to the PROFIBUS DP module.
4.7.4.3 Delimiter
This frame type is suitable for receiving the data frame with fixed frame header and end. It requires the serial devices to first send
one "start byte" to indicate. Serial devices start to send one frame and continue to send one "end byte" when considering one frame
data is over. If this frame type is selected, the PROFIBUS DP module automatically launches the character timeout function.
Under the following conditions, the PROFIBUS DP module considers that it has received one frame data:
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No character timeout happens in the process of receiving bytes. And,
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One correct "start byte" is received. And
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One correct "end byte" is received.
Under other conditions, the PROFIBUS DP module directly discards the incomplete data frame.
Danfoss A/S © 2023.09
PROFIBUS DP
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