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Accessories ► Readers ► SK-300 ► Installation ► Base station at RS-485 ► X2 & X3 RS-485 Pinning
The RS422/RS-485 interface of the devices is provided at terminals 1-8 at the X2 and X3 terminal blocks. The signals have the following meaning:
Pin
|
Name
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Definition
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1
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TxD-b
|
Data/Out - the data is sent from here. Negated signal
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2
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TxD-a
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Data/Out - the data is received here.
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3
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RxD-b
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Data/In, this is where the data is received. Negated signal
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4
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RxD-a
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Data/In, this is where the data is received.
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5
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TxD-b'
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Direct connection to TxD-b, required for the provision of an RS-485 bus.
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6
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TxD-a'
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Direct connection to TxD-ab, required for the provision of an RS-485 bus.
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7
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RxD-b'
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Direct connection to RTxD-b, required for the provision of an RS-485 bus.
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8
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RxD-a'
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Direct connection to RTxD-a, required for the provision of an RS-485 bus.
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 Termination ET/MT-xx6, ET/MT-xx6-Fx/Tx
The S3 and S4 dip switches activate the bus termination resistors of the COM1 and the COM2 with an RS-422 or RS-485 connection.
Switch
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Position
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Interface
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Function
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S3-1
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OFF
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COM1
RS-422/485
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No bus terminator resistor set
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ON
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Bus terminator resistor TxD line
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S3-2
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OFF
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No bus terminator resistor set
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ON
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Bus terminator resistor RxD line
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S4-1
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OFF
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COM2
RS-422/485
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No bus terminator resistor set
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ON
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Bus terminator resistor TxD line
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S4-2
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OFF
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No bus terminator resistor set
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ON
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Bus terminator resistor RxD line
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If the HMIs communicate via MPI,
the S3-1 and S4-1 dip switches must NOT be set to ON.
Otherwise, communication between PLC and control system
cannot be guaranteed to run smoothly.
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Termination ET/MT-xx6-A-...
The S3 dip switches activate the bus termination resistors of the COM1 with an RS-422 or RS-485 connection.
Switch
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Position
|
Interface
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Function
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S3-1
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OFF
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COM1
RS-422/485
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No bus terminator resistor set
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ON
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Bus terminator resistor TxD line
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S3-2
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OFF
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No bus terminator resistor set
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ON
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Bus terminator resistor RxD line
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S4-1
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S4-2
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S4-3
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Interface
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Keying
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0
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0
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0
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RS-422
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Automatic keying
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0
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1
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0
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Keying always on
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0
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0
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1
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Keying enabled by SW
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0
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1
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1
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Driver inactive
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1
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0
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0
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RS-485
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Automatic keying
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1
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1
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0
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Status not permitted
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1
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0
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1
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Keying enabled by SW
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1
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1
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1
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Driver inactive
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Touch switched off:
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S4-4 *
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OFF
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Touch *
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Touch switched off
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ON
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Touch switched on
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*
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It is currently not possible to switch off the touch via the S4-4 dip switch.
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