PM550 CIM Requirements
A-2
TIWAY 1 TI505 NIM User Manual
NOTE
All Siemens tap housings contain factory-installed termination
resistors. If the Tap Housing is not used to terminate the Local Line, the
terminating resistors must be removed when the output cable is
attached.
A.3.1
Networks with Switch-biased Devices and CIMs
On networks using devices with the bias switch, CIMs, and self-biased devices, a bias
must be applied to the line using the switch-biased device as described in the previous
section. All CIMs on the network should be positioned somewhere between the two
outermost switch-biased devices. (See Chapter 2.)
Terminate the network according to the instructions in Chapter 2.
A.3.2
Networks with Only Self-biasing Devices and CIMs
On networks using devices without the bias switch, bias must be applied to the Local
Line by the CIM. To accomplish this, proceed as follows:
1.
On networks having only one CIM, place this CIM at one end of the Local Line
trunk, and install the jumpers provided with the CIM in accordance with the
instructions in the PM550 CIM User’s Manual, Manual Number
PM550–1101154–4. This will apply the correct bias to the Local Line to prevent
oscillations of the CIM receivers.
To terminate the Local Line, replace the existing terminating resistors inside the
CIM T-Tap housing. Connect 150-ohm resistors between the LLM+ and the cable
shield, and also between LLM– and the cable shield. This resistance value is 150
ohms in each instance, and the connection is made in accordance with
instructions inside the tap housing. The combination of termination resistors in
the CIM, together with these 150-ohm resistors, provide the correct Local Line
termination. Then, terminate the other end of the local line as described in
Chapter 2.
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