Isotech VENUS 4951 BASIC, Руководство по обслуживанию, Страница: 31 / 37

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16 Using The PC Interface
The 4000 series models include an RS422 PC interface and a special converter cable that allows
use with a standard RS232 port. When using the bath with an RS232 port it is essential that this
converter cable is used. Replacement cables are available from Isotech, part number ISO-232-
432. A further lead is available as an option, Part Number ISO-422-422 lead which permits up
to 5 instruments to be daisy chained together.
The benefit of this approach is that a number of calibration baths may be connected together in
a "daisy chain" configuration - and then linked to a single RS232, see diagram.
Note: The RS 422 standard specifies a maximum lead length of 1200M (4000ft). A true RS422
port will be required to realise such lead lengths. The Isotech conversion leads are suitable for
maximum combined lead lengths of 10M that is adequate for most applications.
16.1 Connections
For RS232 use simply connect the Isotech cable.
RS422 Connections
Pin Connection
4 Tx+ A
5 Tx- B
8 Rx+ A
9 Rx- B
1 Common
16.2 Protocol
The instruments use the "Modbus Protocol"
If required, e.g. for writing custom software the technical details are available from our
Document Library at www.isotech.co.uk