SATs and ALARM Units on the Same Node
Alarm units and SAT units both utilize the same 9760 Alarm Con- figuration File. The following statements compare and contrast similarities and differences between the two units:
One Alarm unit can handle 64 alarm inputs per unit. One SAT unit can handle 16 alarm inputs per unit.
Alarm units (up to four) may be
Alarm units can interface 256 alarms per port.
SAT units can interface 16 alarms per port.
Up to 10 ports may utilize Alarm units, for a total of 10 X 256 or 2560
SAT units may attach to as many ports as are available, how- ever, the combined
Alarm units utilize alarm base addressing.*
SAT units do not.
Alarm units are added to the system on a 4 per port basis. SAT units are added on a 1 per port basis.
The important thing to consider between ALARM and SAT units is what they share or have in common, which is the ALARM file. Several ALARM file configurations, based on various equipment configurations, are illustrated in Figure
*INFORMATION BOX – Alarm Base Addressing
■Fact 1: Alarm base addressing is used with alarm units only.
■Fact 2: The number entered in the Alarm Base Number box (for alarm units) corresponds to a number in the physical alarm input column of the Alarm configuration file (See Figure
Definition: The Alarm Base Number defines the starting point from which alarm “counting” begins for alarm base addressing as applied to alarm units. Alarm units utilize alarm base addressing in
Working Rules:
■Rule 1: The Alarm Base Number for the first alarm unit attached to a CC1 port is set to 1. Subsequent alarm units (up to four) are
■Rule 2: If you add another alarm unit (say, number five), you must attach it to a different port. You must also enter a new num- ber to count from in the Alarm Base Number box for the port to which this alarm unit is attached. In this case, that number would be 257. Subsequent alarm units (up to four, total, for this port) would utilize alarm addresses
■Rule 3: The combined total of hardwired
■Rule 4: It is best to define alarms for Alarm units before those for SATs, as is done in the first two configuration examples below.
One SAT unit and one ALARM unit on the same node:
One SAT unit and two ALARM units on the same node:
Two SAT units and one ALARM unit on the same node:
Figure
Various
As stated earlier, SAT alarm definitions do not use nor depend upon alarm base addressing. So the following question might arise: If you had one ALARM unit that used only the first 48 inputs of the Alarm file, could you take unused inputs 49 through 64 and use them as SAT alarm inputs?
The short answer: Yes, you can use any alarm input for the SAT as long as it is not actually configured for use by any other piece of equipment.
The long answer: If you are not pressed for port space, it is not a good thing to do. The obvious problem is that (1) you create an alarm assignment overlap from the
however, that is a different story. That leads to problem (2), which is that there now is one more item of information to track. If more alarm units are
numbers already allocated to ALARM unit use, whether they are used or not.
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