Pfeiffer Vacuum HISCROLL 12, Operating Instructions Manual

Page: 35 / 84

Connecting Pfeiffer Vacuum control units or a PC
► Use the connection cable from the scope of delivery of the control unit or from the
Pfeiffer Vacuum
accessories .
► Connect a control unit to the RS-485 interface.
► Connect a PC via the USB/RS-485 converter.
PC D-Sub
1 2 3 4
Fig. 13: Cross-link via connection RS-485 using connection cables and accessories
1 RS-485 to M12 adapter 3 M12 to M12 interface cable
2 Y-connector for RS-485 4 USB RS-485 converter
Networking as RS-485 bus
The group address for the electronic drive unit is 902 .
1. Install the devices according to the specification for RS-485 interfaces.
2. Make sure that all devices connected to the bus have different RS-485 device addresses
[P:797] .
3. Connect all devices with RS-485 D+ and RS-485 D- to the bus.
6.5 Pfeiffer Vacuum protocol for RS-485 interface
6.5.1 Telegram frame
The telegram frame of the Pfeiffer Vacuum protocol contains only ASCII code characters [32; 127], the
exception being the end character of the telegram C
R
. Basically, a master (e.g. a PC) sends a tele-
gram, which a slave (e.g. electronic drive unit or gauge) responds to.
a2 a1 a0 * 0 n2 n1 n0 l1 l0 dn ... d0 c2 c1 c0 C
R
a2 – a0 Unit address for slave
● Individual address of the unit ["001";"255"]
● Group address "9xx" for all identical units (no response)
● Global address "000" for all units on the bus (no response)
* Action according to telegram description
n2 – n0 Pfeiffer Vacuum parameter numbers
I1 – I0 Data length dn to d0
dn – d0 Data in the respective data type (see chapter “Data types”, page 37) .
c2 – c0 Checksum (sum of ASCII values of cells a2 to d0) modulo 256
C
R
carriage return (ASCII 13)
Interfaces
35/84