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Leuze electronic
MA 258
i
55
TNT
35/7-2
4
V
10.2.2
Detailed description of the bits (input byte 0)
Bit 0: Write-Acknowledge: W-ACK
This bit is only relevant for writing slave data in blocks, see chapter 11.1.2 (buffer data on
RS 232). It toggles when data from the PLC are sent to the MA with CTB or SFB.
Bit 2: Service mode active: SMA
Bit 3: Data exist: DEX
This bit is only relevant for reading slave data in Collective mode relevant, see chapter 11.1.1.
Input data
Description
Addr.
Data
type
Value range
Default
W-ACK
W
rite
-Ack
nowledge
(write confirmation)
Write handshake
Indicates that the data was successfully sent by the PLC to
the gateway.
Write-Acknowledge is indicated via this bit. The W-ACK bit
is toggled by the fieldbus gateway whenever a transmit com-
mand has been successfully executed. This applies both for
the transmission of data to the transmit buffer with the CTB
command and for sending the transmit buffer contents with
the SFB command.
0.0
Bit
0->1: Successfully
written
1->0: Successfully
written
0
Input data
Description
Addr.
Data
type
Value range
Default
SMA
S
ervice
m
ode
a
ctive (SMA)
The SMA bit is set if the service switch is set to "MA" or
"DEV", i.e. if the device is in either fieldbus gateway or Leuze
device service mode. This is also indicated by a flashing PWR
LED on the front side of the device. Upon changing to the nor-
mal operating mode "RUN", the bit is reset.
0.2
Bit
0: Device in
operating mode
1: Device in service
mode
0h
Input data
Description
Addr.
Data
type
Value range
Default
DEX
D
ata
e
xist
(data in transmit buffer)
Indicates that further data is stored in the transmit buffer
which is ready for transmission to the control. This flag bit is
always set to high ("1") by the fieldbus gateway as long as
data is in the buffer.
0.3
Bit
0: No data in the
transmit buffer
1: Further data in
the transmit buffer
0h
