CAL Controls CALCOMMS 9300 User Manual

Installation/Cabling
Installation/Cabling
4
Bias resistors
–
Tx
Rx
+
+
–
+
–
+
–
Tx
Rx
+
–
+
–
Tx
Rx
+
–
+
–
Tx
Rx
Instrument 1 Instrument 2 Instrument ‘N’
+5V
620Ω
-5V
620Ω
Bias resistors When transmission lines are not transmitting,
they remain in an indeterminate state which can allow
receivers to receive invalid data bits due to electrical noise
on the cable. To prevent this, the the lines should be forced
into a known state by fitting two 620 ohm bias resistors to
one point (node).
If an RS-485 interface card is being fitted to the PC,
separate bias resistors may not be needed because they
may already be fitted to the card. Check the manufacturers
specification.

CAL Controls CALCOMMS 9300 Specifications

General

Brand	CAL Controls
Model	CALCOMMS 9300
Category	Temperature Controller
Language	English