6 “Modbus” protocol
NOTICE
Property damage on the electronics
Separating all plug-and-socket connections within the bus system with voltage supply switched on
may lead to the destruction of electronic components.
► Always disconnect the voltage supply before removing the connecting plug.
► After switching off the power supply pack, wait until the residual load has dispersed completely
before disconnecting the plug-and-socket connection.
The 9-pin D-Sub connection with the "Modbus" designation provides the option to start/stop the vacuum
pump, select the four pre-set rotation speeds and request the status values of the vacuum pump, e.g.
current, voltage and operating hours.
V
1
2
4
5
6
7
8
9
3
Fig. 8:
D-Sub socket on electronic drive unit, 9-pin
Pin
Function
Description, factory setting
1
DO
Digital Output
2
Ground (GND)
Ground connection
3
-
N/A
4
RS-485
Status request (D+)
5
RS-485
Status request (D-)
6
DI4
Preset rotation speed DI2/DI4:
0/0: Rotation speed 1 = 1800 rpm
1/0: Rotation speed 2 = 1600 rpm
0/1: Rotation speed 3 = 1350 rpm
1/1: Rotation speed 4 = 1150 rpm
Logic 0 = input voltage 0 – 4 V DC
Logic 1 = input voltage 8 – 30 V DC
7
DI2
8
DI1
open: Stop; closed: Start
9
+24 VDC output
Voltage supply
Tbl. 7:
Plug arrangement of the D-Sub socket, 9-pin
“Modbus” protocol
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