turck BL20 Series - 12.3.6 Process output data

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12.3.6 Process output data
The data received from the PLC are loaded into the 64-bit transmit-buffer in the RS232-module.
The transmission is realized in a 8-byte format which is structured as follows:
 1 control byte is required to ensure trouble-free transmission of the data.
 1 byte contains, signals to start the flushing of transmit- and receive buffer.
 6 bytes are used to contain the user data.
n = offset of input data; depending on extension of station and the corresponding fieldbus.
process input data
Byte Byte
DP/PN
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Control byte
n n + 7 STATRE
S
RX_CNT_ACK TX_CNT TX_BYTE_CNT
Flushing of receive- or transmit-buffer
n + 1 n + 6 reserved TXBuf
Dis
RXBUF
FLUSH
TXBUF
FLUSH
Data bytes
n + 2 n + 5 TX_data byte 0
n + 3 n + 4 TX_data byte 1
n + 4 n + 3 TX_data byte 2
n + 5 n + 2 TX_data byte 3
n + 6 n + 1 TX_data byte 4
n + 7 n TX_data byte 5
Designation Value Description
STAT 0-1 1: The communication with the data terminal equipment (DTE) is not
disturbed.
0: The communication with the data terminal equipment (DTE) is dis-
turbed. A diagnostics message is sent only if the parameter ”Deactivate
diagnostics = no/0“.
The diagnostic data show the cause of the communication distur-
bance.
The user has to set back this bit in the process output data by using
STATRES.
TX_CNT_ACK 0-3 The value TX_CNT_ACK is a copy of the value TX_CNT. The value
TX_CNT was transferred together with the last data segment of the
process output data.
The value TX_CNT_ACK is a confirmation of successful acceptance of
the data segment using TX_CNT.
RX_CNT 0-3 This value is transferred together with every data segment. The
RX_CNT values are sequential:
0001101100…
(decimal: 01230…)
Errors in this sequence show the loss of data segments.
RX_BYTE_CNT 0-7 Number of the valid bytes in this data segment.