Setup
91369 Service Manual 2-8
SDLC Bus Termination
The SDLC bus must be properly terminated for correct operation. If no external devices (for example, Flexports
or multigas analyzers) are connected, proper termination of the SDLC bus is accomplished automatically. If
external devices are connected, the switch on the module housing farthest from the monitor must be set to the
terminated ( ) position. All others must be set to the non-terminated ( ) position. The SDLC clock and
data signals are switched by the terminator switches and are not present “downstream” of any switch set to the
position.
Figure 2-5: Terminator switch settings
Because bus termination is handled by setting the switches appropriately, an external terminator is only
required when external devices are connected.
If external devices are connected, an external cable terminator is required to terminate the SDLC bus. This
must be installed at the end of the SDLC bus (following the last external device). In this case, all module
housings must have their switches in the position.
Note:
Flexports require a powered Flexport cable (P/N 012-0555-00) when used with the 90491/90499 module
housing or 91369 monitor. SDLC data is only passed along to the external device(s) when the terminator
switch (SW2) is in the
position.
Alarm Relay
Alarm output signals are available at the Nurse Alert ( ) connector instantaneously when an alarm occurs.
Table 3 describes the connector pinouts for remote alarms. Figure 2-6, Figure 2-7, and Figure 2-8 illustrate the
circuits for each alarm function.
External Alarm Pinout
Alarm connector pinouts are as follows:
Table 3: Connector Pinouts
Pin
Alarm Circuit Meaning
1
Alarm 0 (high priority)
Common
2 Normally Closed
3 Normally Open
4GND
Non-terminated Terminated
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