5. CONFIGURATION
Configuration Description Default Options
Serial Mode
Sets the serial port operation
mode configuration.
Normal Mode
- Extended Mode: Extended
operation mode which de-
livers information regarding
the received data frame.
- Normal Mode: Serial com-
munication normal opera-
tion mode.
Table 56: RS-232 Standard Serial Configuration
Notes:
Extended Mode: This serial communication operation mode provides information regarding the data frame received. The
information available is the following:
One byte for the received data (RX_CHAR : BYTE): Store the five, six, seven or eight bits from the data received,
depending on the serial communication configuration.
One byte for the signal errors (RX_ERROR : BYTE): It has the format described below:
• Bit 0: 0 - the character in bits 0 to 7 is valid. 1 - the character in bits 0 to 7 is not valid (or it cannot be valid), due
to problems indicated in bits 10 to 15.
• Bit 1: Not used.
• Bit 2: Not used.
• Bit 3: UART interruption error. The serial input remained in logic 0 (space) for a time greater than a character
(start bit + data bits + parity bit + stop bits).
• Bit 4: UART frame error. The logic 0 (space) was read when the first stop bit was expected and it should be logic
1 (mark).
• Bit 5: UART parity error. The parity bit read is not correct according to the calculated one.
• Bit 6: UART overrun error. Data was lost during the FIFO UART reading. New characters were received before
the later ones were removed. This error will only be indicated in the first character read after the overrun error
indication. This means some old data were lost.
• Bit 7: RX line overrun error. This character was written when the RX line was completed, overwriting the unread
characters.
Two bytes for the timestamp signal (RX_TIMESTAMP : WORD): Indicates the silence time, within the 0 to 65535 inter-
val, using 10 us as base. It saturates in 655.35 ms if the silence time is higher than 65535 units. The RX_TIMESTAMP
of a character measures the time from a reference which can be any of the three options below:
• On most of the cases, the end of the later character.
• Serial port configuration.
• The end of serial communication using the SERIAL_TX FB, in other words, when the last character is sent on line.
Besides measuring the silence between characters, the RX_TIMESTAMP is also important as it measures the silence
time of the last character on the RX line. The silence measuring is important for the correct protocol implementation,
as MODBUS RTU, for example. This protocol specifies an inter-frame greater than 3.5 characters and an inter-byte less
than 1.5 characters.
Data Bits: The serial interfaces Data Bits configuration limits the Stop Bits and Communication Parity fields. Therefore,
the stop bits number and the parity method will vary according to the data bits number.
Data Bits Stop Bits Parity
5 1, 1.5
NO PARITY, ODD, EVEN, PARITY ALWAYS
ONE, PARITY ALWAYS ZERO
6 1, 2
NO PARITY, ODD, EVEN, PARITY ALWAYS
ONE, PARITY ALWAYS ZERO
7 1, 2
NO PARITY, ODD, EVEN, PARITY ALWAYS
ONE, PARITY ALWAYS ZERO
87
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