CAMAC 24-Bit Change-of-State Input Register Module

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The 3473 is a single-width CAMAC module providing 24 individually isolated contact sense circuits and change-of-state indication.

The sense circuit detects the presence or absence of voltage at its terminals and is suitable for sensing such remote process contact closures as limit switches, machine tool relay contacts, pressure switches, manual switches, and mercury-wetted contacts.

Four voltage options are available: 12 VDC, 24 VDC, 48 VDC, and 120 VAC.

CAMAC 24-Bit Change-of-State Input Register Module: 3473

3473 Data Sheet

Supporting Chassis

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Input isolation is achieved by using LED/phototransistor optical isolators. Each circuit is a floating two-wire circuit with common-mode voltage isolation greater than 500 volts. Each option has 24 circuits with identical input voltage ratings, and the switching threshold is approximately one half the rated input voltage. Each input circuit draws more than five but less than ten milliamperes. The logic convention is such that a contact closure (input voltage present) is interpreted as a logical "1". Each input is conditioned by filtering after the optical isolator. The filter time constant is 100 milliseconds.

The 3473 contains a 24-bit memory register and a 24-bit comparator. If one or more of the inputs has changed state (1-to-0 or 0-to-1) since the last time the memory register was updated, a common LAM status is set. This can produce a LAM request directing the computer program to read the current state of the inputs.

The 3473 can be used interchangeably with the Model 3471 24-bit Isolated Input Gage if only the F(0)•A(0) Read is used and the LAM request is maintained in a disabled state.

In the initialized state, the input register and the memory register contain the same data pattern. If any input changes state, a not-compare exits and the LAM status is set. This produces a LAM request (if enabled). In response to the LAM request, the program does an F(2)•A(0) command. This reads the new state of the inputs, then updates the memory register to equal the input states, and clears the LAM status.

To determine input state before the recent changes, an F(0)•A(1) command can be performed, reading the state of the memory register. This must be done before the F(2)•A(0) Read.

Note that the first change-of-state sets the LAM status, and no further indication is given (as other inputs change state) until an F(2)•A(0) read-and-clear command is performed. The data staticize latch is disabled during the F(0)•A(0) and F(2)•A(0) commands to prevent ambiguous results if inputs are changing at that time.

CAMAC Module Features

  • 24 Individually Isolated Contact Sense Circuits
  • 24-Bit Voltage Sense
  • Change-of-State Indication
  • Optical Isolation
  • 12, 24, and 48 VDC or 120 VAC Input Options
  • 100 Millisecond Input Filter

CAMAC Module Ordering Information

3473 Products and Part Numbers
Change-of-State Input Register, 120 Vac, 24-Bits,
50S Amphenol Ribbon Connector
Change-of-State Input Register, 48 Vdc, 24-Bits,
50S Amphenol Ribbon Connector
Change-of-State Input Register, 24 Vdc, 24-Bits,
50S Amphenol Ribbon Connector
Change-of-State Input Register, 12 Vdc, 24-Bits,
50S Amphenol Ribbon Connector
Change-of-State Input Register, Contact Input,
24-Bits, 50S Amphenol Ribbon Connector