Baumer NE215 Manual de instrucciones - Página 24

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Open interface description

7.1

General information

The open interface is of the RS485 type. It is possible to send the

commands documented in the „Description of the Open Interface"

for remote control to the counter. The interface allows to call up data

and to change the programming of parameters not relevant for the

values to be calibrated.

In general, the counter is operated via the serial interface on a

personal computer – that is why the external device will be called PC

for short in the following. However, it is also possible to use another

device with similar features.

7.2

Transmission protocol

Transmission is effected character by character in ASCII code. Each

character consists of 8 bits. The 8

parity" , the 8

bit will always be transmitted as a zero. The counter

responds to every request of the PC via the serial interface – if data

have been transmitted correctly.

The transmission of characters is introduced by the start-of-text character

<STX> and closed by the end-of-text character <ETX>. In addition, the

tachometer also sends a <CR> (carriage return) after the character

<ETX>. This allows the input (in high-level languages such as BASIC) of a

complete record of data with only one command. The character <STX> is

followed by an address allotted to the counter. This allows a target

approach of the counter in a serial network. The address is followed by

the indication of the line (position) that is to be read out or programmed.

In case of a programming instruction, the line indication is followed by a

„P" (program) and the data (parameters).

The protocol is split into three groups, as described in the following:

Reading of storage locations (READ instruction):

<STX> Address Line <ETX> [<CR>]

Programming of storage locations (WRITE instruction):

<STX> Address Line P [VZ] Data <ETX> [<CR>]

Special commands:

<STX>

Address Parameter <ETX> [<CR>]

<STX>

Start of Text (02Hex)

Address

00..99 (device address)

Line

01..XX (please refer to operating plan)

Programming command

Print command

Plus/Minus sign, only indicated if value

is negativ

Data

Programming data

Parameter Special commands

<ETX>

End of Text (03Hex)

<CR>

0DHex (Control character „carriage return").

„CR" needs not be indicated (optional),

will however, always be returned by

counter.

NE215

bit is the parity bit; in case of „no