HBM PW15AHi, Инструкция по монтажу, Страница: 18 / 72

PW15AHi
18
A2526-4.0 en/de/fr HBM
7 Interfaces
IMPORTANT
The PW15AHi interface driver relates to GND. The Master interface driver
must also relate to this GND.
A shielded cable must be used as the bus cable. The shield should always
be connected to the housing at both ends. The shield of the PW15AHi cable
is electrically connected to the measuring body (see PW15AHi pin
assignments).
Should it be necessary, a separate cable can be used to establish
potential equalization between the PW15AHi and the (PC/PLC) master
(grounding concept). The cable shielding must not be used for this
potential equalization.
Before installing several PW15AHi into an installation with a bus system, take
the following into account:
The printed production number (typeplate) is required for setting up data
communication. If the typeplate can no longer be seen after installation, the
numbers of each PW15AHi should be noted beforehand. This enables different
addresses to be assigned during the initial start‐up.
Alternatively, before connection to the bus system, you can connect each
PW15AHi individually with a PC, in order to set different addresses (see ADR
command, Online Help).
7.1 RS‐485 4-wire interfaces (UART)
PW15AHi load cells are supplied with an RS‐485 interface. Baud rates of
1200

115200 baud can be set for the interface. The power supply ground
(GND) of the PW15AHi load cell is used as the reference ground for all the
interface signals.
A single PW15AHi load cell can be connected via the RS‐485 interface, or you
can set up a bus system to connect several PW15AHi load cells to an RS‐485
interface. All transducers on a line are switched in parallel and are
differentiated by the software assigning different addresses. If the control
computer has an RS‐232 interface, an interface converter is required (e.g. from
HBM, Order No.: 1‐SC232/422B). The correct assignment of the transmit and
receive lines can be seen in Fig. 7.1 (bus line Ra to Ta of the converter, etc.).
The HBM converter and the PW15AHi both already contain bus termination
resistors. So additional bus termination resistors for for RS‐485 are
not
required. Up to 32 PW15AHi can be connected to one bus.