RS 485 information

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HMIs, human machine interfacesEagle ET/MT-3x6...Connection InformationsRS 485 information

 

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

Definition

1

TxD-b

Data/Out - the data is sent from here. Negated signal

2

TxD-a

Data/Out - the data is received here.

3

RxD-b

Data/In, this is where the data is received. Negated signal

4

RxD-a

Data/In, this is where the data is received.

5

TxD-b'

Direct connection to TxD-b,   *1

6

TxD-a'

Direct connection to TxD-ab,  *1

7

RxD-b'

Direct connection to RTxD-b, *1

8

RxD-a'

Direct connection to RTxD-a, *1

 

*1)

required for the provision of an RS-485 bus.

 

The X2 and X3 ports of our HMIs provide you with the option of using an RS-422 or an RS-485 bus, depending on the wiring. Below is an example of how this works with an RS-485.

 

The RS-485 (today: EIA-485) provides a data transfer interface with differentiated signals. Please note that the RS-485 bus is a bi-directional interface. This means that the interface sends and receives data. Connected devices therefore have to ensure communication can take place.

 

The following illustration shows how it should be connected to the interface:

 

X2_X3_RS-485-Bus

 

Hinweis

Pins 1-5, 2-6, 3-7, 4-8 are already internally connected.

 

Hinweis

The maximum length of the data transmission cable is 1000m.

 

Click to expand or collaps information.   Schalter für den Busabschluß ET/MT-xx6-A-... from rev. 3.0.2

The S3 & S4 dip switches activate the bus termination resistors of the COM1/COM2 with an RS-422 or RS-485 connection.

 

Seriall interface COM1:

Switch

Position

Interface

Function

S3-1

OFF

COM1

RS-422/485

No bus terminator resistor set

ON

Bus terminator resistor TxD line

S3-2

OFF

No bus terminator resistor set

ON

Bus terminator resistor RxD line

 

S4-1

S4-2

S4-3

Interface

Keying

0

0

0

RS-422

Automatic keying

0

1

0

Keying always on

0

0

1

Keying enabled by SW

0

1

1

Driver inactive

1

0

0

RS-485

Automatic keying

1

1

0

Status not permitted

1

0

1

Keying enabled by SW

1

1

1

Driver inactive

Touch switched off:

S4-4 *

OFF

Touch *

Touch switched off

ON

Touch switched on

 

Seriall interface COM2:

Schalter

Position

Interface

Funktion

S3-1

OFF

RS-422/485

No bus terminator resistor set

ON

Bus terminator resistor TxD line

S3-2

OFF

No bus terminator resistor set

ON

Bus terminator resistor RxD line

 

S4-1

S4-2

S4-3

Interface

Keying

0

0

0

RS-422

Automatic keying

0

1

0

Keying always on

0

0

1

Keying enabled by SW

0

1

1

Driver inactive

1

0

0

RS-485

Automatic keying

1

1

0

Status not permitted

1

0

1

Keying enabled by SW

1

1

1

Driver inactive

Function:

S4-4

-

-

not used.

 

Click to expand or collaps information.   Schalter für den Busabschluß ET/MT-xx6-A-... to rev. 3.0.1

The S3 dip switches activate the bus termination resistors of the COM1 with an RS-422 or RS-485 connection.

 

Switch

Position

Interface

Function

S3-1

OFF

COM1

RS-422/485

No bus terminator resistor set

ON

Bus terminator resistor TxD line

S3-2

OFF

No bus terminator resistor set

ON

Bus terminator resistor RxD line

 

S4-1

S4-2

S4-3

Interface

Keying

0

0

0

RS-422

Automatic keying

0

1

0

Keying always on

0

0

1

Keying enabled by SW

0

1

1

Driver inactive

1

0

0

RS-485

Automatic keying

1

1

0

Status not permitted

1

0

1

Keying enabled by SW

1

1

1

Driver inactive

Touch switched off:

S4-4 *

OFF

Touch *

Touch switched off

ON

Touch switched on

 

*

It is currently not possible to switch off the touch via the S4-4 dip switch.

 

Click to expand or collaps information.   Schalter für den Busabschluß ET/MT-xx6 und 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

Position

Interface

Function

S3-1

OFF

COM1

RS-422/485

No bus terminator resistor set

ON

Bus terminator resistor TxD line

S3-2

OFF

No bus terminator resistor set

ON

Bus terminator resistor RxD line

S4-1

OFF

COM2

RS-422/485

No bus terminator resistor set

ON

Bus terminator resistor TxD line

S4-2

OFF

No bus terminator resistor set

ON

Bus terminator resistor RxD line

 

 

Hinweis

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.

 

 

The PIN configuration of the other unit will be detailed in the interface description issued by the unit's manufacturer.

 

cable type:

Data connection at least UTP [unshielded twisted pair] in rough environment STP [shielded twisted pair]

 

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