Using these registers, designated as Input MTU, the data are transferred from the module to the superordinated system.
Control Byte in Receiving Direction
Using these control bytes, the module transmits the required information to the superordinated system to be able to put back together the received frame from the individual Input MTU blocks and segments.
|
Bit |
Description |
|---|---|
|
0–5 |
0–63 = Segment length |
|
6 |
0 = Control byte for the next segment in a new MTU (RxByte1) 1 = Control byte for the next segment follows immediately after the segment end |
|
7 |
0 = Frame is not finished 1 = Frame is finished |
This length specification basically describes the length of the received frame. However, only six bits are available in the control byte, thus 63 is the largest possible partial length here. If the received frame is longer than the maximum segment length, it is split to several segments with the corresponding control bytes. The individual lengths have to be added up. The real frame end is detected by bit 7 in the last segment.
With this information, it is transferred at which position the next control byte is to be expected.
Also see Multiple Segments/Segment Size.
In the last segment, this bit is set as the frame end identifier. Now the application can further evaluate the frame.
