User manual

6 Detailed descriptions of I/O modules | Serial communication module UR20-1COM-232-485-422
392 1432790000/08/12.2015Manual u-remote
Data transfer
The process data length can be parameterised to be 8 or
16Bytes. Byte0 is used for status and diagnosis, Byte1 for
the data segment length and the remaining 6 or 14Bytes
are user data.
Process input data: The data sent from the serial device are
written into the receive memory of the UR20 module. As
soon as the SPS request results in that RX_CNT is not equal
RX_CNT_ACK, the data will be sent in segments via the eld-
bus coupler to the PLC. The successfully data transfer will be
acknowledged to the module.
The receive memory can safe a maximum of 255Bytes. A
software handshake (XON/XOFF) or a hardware handshake
(RTS/CTS) can be parameterised using the ow control, so
that an alarm will warn against a buffer overow.
Process input data UR20-1COM-232-485-422
Byte Format Name Bit Description Remarks
IB0
Word
Status and diagnosis
IX0.0 Data in the receive memory
RX = 0: Receive memory is empty
RX = 1: A telegramm or telegramm segment in the receive memo-
ry is ready for transmission.
IX0.1 Receive memory nearly full
Only 10 characters are left in the receive memory. XOFF will be
set if parametrerised.
IX0.2 Not used
IX0.3 RX_CNT
The RX_CNT value is assigned to each data segment of the
process input data while transmission. The sequence or the
RX_CNT values is:
Binary: 00, 01, 10, 11, 00, ...
Decimal: 0, 1, 2, 3, 0, ...
A faulty data seqence indicates missing data segments.
IX0.4 RX_CNT
IX0.5 TX_CNT_ACK
The TX_CNT_ACK value is a copy of the TX_CNT value, which
has been transferred together with the last data segment of the
process output data. TX_CNT_ACK acknowledges that the data
has been taken over successfully.
IX0.6 TX_CNT_ACK
IX0.7 STAT
STAT = 1: Communication with the device is without fault.
STAT = 0: Faulty communication with the device.
IB1
Length of the data segment /
of the subsequent diagnosis
data
RX Length of the data/diagnosis data in this frame
IB 2 ... IB 7
or
IB 2 ... IB 15
Received data
User data of the transferred
telegramm segment
Process output data: The data sent from the PLC via the eldbus
coupler are written into the transmission memory of the
UR20 module. The module is continously checking whether
data are ready to be sent or a data transfer to the device has
been nished successfully. Not till then the next data will be
transferred.