RS485-FD Converter
Phason
4
Not terminating the last device on the communication channel
– on all systems, the last device
on the communication channel must have the termination resistors in place or a termination
module installed. You must remove the termination resistors from all devices, except the last
one on the communication channel.
The termination resistors are located on the circuit board of all networkable devices, except the
Supra and PBx Power Block. There are no termination resistors on Supras and PBx Power
Blocks; those controls must have a Termination Module installed on the last device. The
Termination Module connects to the communication socket on the last device. For information
about Termination Modules, contact your dealer or Phason Customer Support.
The termination resistors on Power Block models PB-1 to PB-6 are in sockets on the Micro
Board and can be removed and replaced if necessary. Termination resistors on all other models
must be removed using wire cutters. For more information about the location of termination
resistors, see the installation guide for your specific product.
If you remove the termination resistors from the last device by mistake, you will have to install a
Termination Module on that device.
Using shielded twisted pair (STP) cable
The advantage of using STP cable is that it can improve communications by reducing
electromagnetic interference. The drawback of STP cable is that it requires more care during
installation. If the shielding is connected incorrectly, shielded cable can cause more problems than it
solves.
How to install shielded cable
When installing shielded cable, you must connect the shielding to the building ground at one end
only. Phason recommends connecting the cable to the building ground near the computer.
When connecting the devices along the communication channel (daisy-chain), connect the shielding
of the incoming cable to the shielding of the outgoing cable. Do not connect the shielding to the
device or to anything else. At the last device on the daisy chain, do not connect the shielding; leave it
unconnected.
