ESD electronic CAN-CBM-PLC/331-1, Hardware Manual

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Data Transfer
CAN-CBM-SIO, CAN-CBM-SIO4 Software Rev. 1.0 2 - 1
2. Description of the Data Transfer
The serial data are buffered between the CAN-bus and the serial interfaces in both data directions and
by means of a 256 bytes sized toroidal-core store for each channel. The data being received first are
also transmitted again first.
If the toroidal-core store is full and further data is received, it will be lost. Therefore, it is important to
match the transmission rates of CAN-bus and serial interfaces with each other.
2.1 Serial Interfaces Transmit Data
The amount of CAN-bus data to be stored in the toroidal-core store per interval, has to be smaller than
the amount of data transmitted by the serial interfaces.
The amount of received data per interval depends on the amount of data bytes transmitted, the
frequency of transmissions, the bit rate of the CAN-bus and the assigned bus enabling of the CAN-bus.
If data is lost during operation, the intervals between transmission are to be prolonged or/and the
amount of transmitted bytes has to be decreased.
The data is transmitted to the module by the CAN-bus via the Rx-identifiers or via COBs 1 to 4. The
user is free to select the amount of bytes to be transmitted.
esd Prot. CAL
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
RxId COB
RxId 1 COB 1 Data for serial interface channel 1
RxId 2 COB 2 Data for serial interface channel 2
RxId 3 COB 3 Data for serial interface channel 3
RxId 4 COB 4 Data for serial interface channel 4
RxId 5 COB 5 Data for serial interface channel 5
Table 2.1.1:
Receiving the data to be transmitted via Rx-identifiers or COB 1 to 5 (CAN-CBM-
SIO4)
Attention:
The terminal interface (at DSUB9) on the CAN-CBM-SIO4 module has been assigned with Rx-
identifier RxId
5
and Tx-identifier TxId
5
. On the CAN-CBM-SIO module with only one serial
interface, however, the terminal interface has been assigned with Rx-identifier RxId
1
and Tx-
identifier TxId
1
.