Systems Reference Library - All about the IBM 1130 Computing ...

1851 MULTIPLEXER TERMINAL, MODEL 2: Thisterminal is similar to the model 1. However, amaximum of 62 multiplexer points is allowed, anda cold junction is provided for direct connection ofthermocouples. A cold-junction temperature indicatordevice (resistance bulb thermometer) is includedin the terminal.MULTIPLEXER (RELAY): This multiplexer (Mpx/R) provides switching for both high-level differentialinputs and low-level differential inputs, allowing allMpx/R inputs to use a common ADC.MULTIPLEXER (SOLID STATE): This multiplexer(Mpx/S) is a solid state, high-level single-endedmultiplexer. Mps/S provides high-speed switchingof analog input signals to allow use of a commonADC.MULTIPLEXER OVERLAP: This feature allowsoverlap of solid state and relay multiplexing.MPX /R CONTROL AND MPX/R CONTROL ADDI-TIONAL: These features provide the control circuitrynecessary to operate the Mpx/R points. Eachfeature can control up to 256 points.MPX/S CONTROL: Control circuitry to operate theMpx/S points is provided by this feature.DIFFERENTIAL AMPLIFIER: This is a time-sharedamplifier which raises each low level signal to thevolt level of the ADC. Up to 256 Mpx/R pointscan use the same amplifier. The differential amplifiermay be assigned one of the following ranges:±10 mV, ±20 mV, 150 mV, 1100 mV, ±200 mV, or±500 mV.ADC MOD 1: This ADC converts analog signals (±5volt range) to digital values (8, 11, or 14 bits plussign).ADC MOD 2: This ADC is similar to ADC Mod 1but includes a sample-and-hold amplifier for increasedconversion rates.AI DATA CHANNEL ADAPTER 1: This adapterallows sequential reading of input points by meansof data channel (cycle steal) operations with oneXIO initialize read.AI DATA CHANNEL ADAPTER 2: This adapter, inconjunction with adapter 1, allows random readingof input points via data channel (cycle steal) operationswith one XIO initialize read and one XIO initializewrite.COMPARATOR: The comparator performs rangechecking on digital values developed by the ADC.The high and low limits are selectively obtainedfrom the processor-controller for checking. Whenthese values are determined to be out of limit, aninterrupt informs the P-C. Only one P-C cycle isrequired for each value to be limit checked.ANALOG INPUT EXPANDER: Allows a completeanalog input system to be configured around the1826 Data Adapter Unit. Thus, a second ADC orsimply a remotely located ADC may be added to any1800 system.MULTIPLEXER/R AND MULTIPLEXER/S MAXI-MUMS AND RANGES: Althrough the maximum numberof Mpx/R points and Mpx/S points is 1,024 and256, respectively, both maximums cannot be installedwithin the same system. The simultaneousmaximums for each system are dependent upon thenumber of analog input ranges as shown in Figure 32.IBM 1851 MULTIPLEXER TERMINALThe 1851 Multiplexer Terminal is a modular chassisin which multiplexing and signal conditioning featurescan be mounted. The 1851 terminals are mounted inan 1828 Enclosure. Up to 19 terminals can be includedfor any one ADC in a system. Mpx/R andMpx/S cannot be installed in the same 1851 terminalunit.Two models of the multiplexer terminal areavailable. The model 1 provides facilities for up to64 multiplexer points in groups of 16 points. Customerwires are terminated on screw-down terminals.The signal matching elements are available for eachmultiplexer terminal. Up to two differential amplifierscan also be mounted in each terminal.The model 2 is modified to allow for thermocoupletermination, cold junction thermal stabilization,and a resistance bulb thermometer (RBT)circuit. These elements are used to determine coldjunctiontemperature. Thus, thermocouple wirescan be connected directly to the terminals, and thecold-junction temperature can be computed by theP-C.The first two multiplexer addresses installed ina model 2 are used for the cold-junction signal measurement:00 is RBT reference; 01 is RBT bridgeoutput. These two signals should be read at intervalswhich are small compared with significantambient temperature change intervals. Separatereadings are required for each model 2.Since the first two addresses are used for thecold junction, a maximum of 62 input points areAnalog Input 93