IBM System/7 Functional Characteristics - All about the IBM 1130 ...

The significant bits in the ISW and their meanings are:Significant Bits Meaning3 Analog-to-digital converter inoperative.5 Multiple relays selected. This multiplexer failure is caused by morethan one input being selected during the conversion cycle.6 No relays selected. This multiplexer failure results from no input beingselected during the conversion cycle.7 Overload. The voltage read by the ADC was greater than the inputvoltage range selected by the amplifier.12 Device busy. The analog input control is converting an input voltage.13 Device end. The conversion operation requested is complete. If errorconditions occur during the execution of such operations asanalog-to-digital conversions, this bit is set on along with othererror identifying bits.15 Invalid multiplexer address. An input point was addressed that wasnot installed.ANALOG INPUT CONTROL MODEL CThe analog input control model C converts analog signals into binary values of 14 bitsplus sign. These analog signals can be within the range of ±10 mV full scale to ±5.12Vfull scale. In the multifunction module, analog input control model B and model C aremutually exclusive.The analog input function is accomplished by ad analog-to-digital converter (ADC), anamplifier, and a differential solid-state multiplexer.The solid-state multiplexer can have as many as 32 two-wire differential analog inputpoints, in eight groups of four points each. With high-level inputs (±5.12V), a speed of20,000 points per second can be attained. An input speed of 14,000 points per secondcan be achieved with low-level inputs (10 to 640 mV). A scanning speed of 7,000points per second can be obtained with the use of automatic gain selection. The actualscanning rate obtained, however, depends on the input voltage value, the physical locationof the I/O module, and the programming techniques used. Conversion time required bythe ADC varies from 25 to 46 microseconds, depending on the input voltage. Additionaldelays due to module location and programming must also be considered when computingthe actual scanning rate.One amplifier is required to service all of the analog input points. If all analoginputs are at the ±5.12V level, the high-level-only amplifier is used. If a range ofvoltage levels must be accommodated, a multirange amplifier is used. The multirangeamplifier can be program controlled to one of the seven different ranges, or to automaticallyselect the appropriate amplifier gain. When the amplifier is programmed to automaticallyselect the gain, analog signal resolution is reduced to 12 bits plus sign if the selectedgain is returned (binary encoded in three bits) to the program with the data. The multirangeamplifier allows conversion of signals in the ±10 mV, ±20 mV, ±40 mV, ±80 mV, ±160 mV,±640 mV, and ±5.12 V ranges. (See Appendix E for conversion of an analog voltage to itsbinary equivalent for the amplifier range selected.)The analog-to-digital converter furnishes an overload indication in the data word whenthe signal level falls outside of a range that can be converted.A temperature reference attachment is available for use in the cold junction compensationof thermocouple inputs.IBM 5012 Multifunction Module Model Al 13-9