Data Transfer - GE EP-5261 User Manual

Serial communication module
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6
GFK-2992B

Data Transfer

The process data length can be parameterized 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 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 fieldbus
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 flow control, so that an alarm will warn against a buffer overflow.
Process output data: The data sent from the PLC via the fieldbus coupler are written into the transmission memory of
the module. The module is continously checking if data is ready to be sent or a data transfer to the device has
completed successfully. Not until then will the next data will be transferred.
Byte
Format
IB0
Word
IB1
Word
IB 2 ... IB
7
or
IB 2 ... IB
15
Process Input Data
Name
Bit
IX0.0
IX0.1
IX0.2
IX0.3
Status and
Diagnosis
IX0.4
IX0.5
IX0.6
IX0.7
Length of the
data segment
/ of the
subsequent
diagnosis data
Received data
For public disclosure
RSTi-EP Slice I/O Serial Communication Module
Description
Notes
RX = 0: Receive memory is empty
Data in the receive
RX = 1: A telegram or telegram
memory
segment in the receive memory is
ready for transmission.
Only 10 characters are left in the
Receive memory
receive memory. XOFF will be set if
nearly full
parametrerised.
Not used
The RX_CNT value is assigned to each
data segment of the process input
RX_CNT
data while transmission. The sequence
or the RX_CNT values is:
Binary: 00, 01, 10, 11, 00, ...
Decimal: 0, 1, 2, 3, 0, ...
RX_CNT
A faulty data seqence indicates
missing data segments.
The TX_CNT_ACK value is a copy of the
TX_CNT_ACK
TX_CNT value, which has been
transferred together with the last data
segment of the process output data.
TX_CNT_ACK
TX_CNT_ACK acknowledges that the
data has been taken over successfully.
STAT = 1: Communication with the
device is without fault.
STAT
STAT = 0: Faulty communication with
the device.
Length of the data / diagnosis data in
RX
this frame
User data of the
transferred telegram
segment

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