Baumer NE215 - Manual (Page 24)

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NE215 Open interface description
7 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
th bit is the parity bit; in case of „no
parity“, the 8 th 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:
a) Reading of storage locations (READ instruction):
<STX> Address Line <ETX> [<CR>]
b) Programming of storage locations (WRITE instruction):
<STX> Address Line P [VZ] Data <ETX> [<CR>]
c) 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)
P Programming command
D Print command
VZ 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.