The Data Acquistion system uses both epoxy-encapsulated 

 semiconductors and Flat- Pack style micrologic elements. The 

 tape is produced by a Digi-Data model DSR-1400 incremental 

 tape recorder with a recording density of 556 characters per inch 

 of tape. At the fastest data- acquisition speed of one measurement 

 per second, a 2400 foot reel of tape will therefore hold about 20 days 

 worth of data. At slower data- acquisition speeds, the tape will 

 last proportionately longer. 



3.3.1 Functional Operation 



The Data Acquisition System makes a complete measurement, 

 which includes the recording of electrical resistance as well as 

 of identification numbers every N seconds. This Measurement 

 Interval may be any integral number of seconds from 1 to 64 seconds, 

 The Measurement Interval is set by switches on the front panel of 

 the System. Each time the System takes a Measurement, it indexes 

 to a new sensor. It thus cycles through all of the sensors on the 

 array in a regular sequence. Seven electrical resistance measure- 

 ments are taken on the Signal Cable. Each sensor is therefore 

 measured every 7N seconds. 



Every resistance measurement has associated with it two iden- 

 tification numbers, called the Sensor Number and the Measurement 

 Number. These two numbers are held in binary form in registers 

 within the Data Acquisition System, and both are incremented by 

 1 during each Measurement Cycle (the sequence of operations in- 

 volved in recording on tape a single Measurement - data plus 

 identification numbers - is called a Measurement Cycle). The 

 Sensor Number ranges from to 6 and indicates which of the seven 

 inputs from the array is being measured. After measuring input 6, 

 the Sensor Number register resets to input 0. The Measurement 

 Number ranges from 000 to 251, and simply numbers each of the 

 252 Measurements in a Block of data on the Primary Data Tape. 

 The actual manner in which these operations are carried out may 

 be seen from Figure 3-17, which is a flow diagram of system op- 

 erations. Figure 3-18 shows the actual format of data as recorded 

 on the Primary Data Tape. 



If desired, the resistance measurement may be replaced during 

 a single Measurement Cycle by a 16-bit External Data Word, which 

 is entered from the front panel. This is accomplished simply by 



214 



