GE EP-5261 - Data Transfer

6 RSTi-EP Slice I/O Serial Communication Module
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.
Process Input Data
Byte
Format
Name
Bit
Description
Notes
IB0
Word
Status and
Diagnosis
IX0.0
Data in the receive
memory
RX = 0: Receive memory is empty
RX = 1: A telegram or telegram
segment in the receive memory 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 Word
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 telegram
segment
For public disclosure