【 Product Details 】
The VMIVME-3122 is a member of VMIC’s extensive analog input/output family
VMEbus products. With 16-bit digital resolution, programmable gain, selectable conversion rates, and automatic scanning of 64 differential or single-ended analog inputs, the VMIVME-3122 offers superior dynamic range and analog input channel density. Supports multiple modes of operation, including automatic scanning, data burst, and external synchronization. This board is designed to interface directly with VMIC’s signal conditioning board wire for digitized thermocouple, rtd and strain gauge output.
A single channel gain can be downloaded for use during a scan operation, or the board can be configured as a fixed gain common to all channels. Multiple boards can be synchronized together. A maximum of 16 boards can be synchronized to start each scan at the same time. An interval timer, bus interrupter, channel counter, and Midscan/Endscan flag simplify the monitoring of port data buffers for data within dual channels. System application features that can benefit from VMIVME-3122 include factory automation, process control, data acquisition systems, training simulators and laboratory instruments. The following is a brief overview of the main features, illustrating flexibility and
VMIVME-3122 provides:
•16,32 or 64 differential or single-ended analog inputs
• 16-bit A/D conversion
•381 Hz to 100 kHz Selectable scan rate for high performance option, 381 Hz
Standard performance options up to 50 KHZ
• Programmable gain x1 or x10
Features of VMIVME-3122 (continued):
•A/D converters range from ± 2.5V, ±5v, ±10v,0 to +5v,0 to +10v
• Programmable channel gain
•16 to 1,024 word dual-port data buffer
Short I/O(A16), standard (A24), or extended (A32) data space operations
• Programmable channel block size and buffer size
• Optional low-pass input filter
• Continuous and burst operating modes
• Free running or external/internal triggering
•Midscan or Endscan indicates the bus interrupter
• Programmable interval timer to time data bursts
• Direct wiring from VMIC signal conditioning board
• Reset after initialization in automatic scan mode gain =x1
Function description
The VMIVME-3122(Figure 1 on page 15) is a high-resolution 16-bit 64-channel analog scanning and digitizing pad for VMEbus systems. Dual-port data memory, onboard timer, automatic control gain and programmable bus interrupts enable the VMIVME-3122 to support a wide range of analog input traffic, with minimal host processor involvement. Analog inputs are scanned and sequentially digitized. The numeric values are stored in a two-port data buffer that can be accessed from the VMEbus at any time. Each channel can be programmed individually or set in software to fix a gain common to all channels. The channel gain is software-optional x1 or x10. The A/D converter voltage range is ± 2.5V, ±5v, ±10v,0 to 5v, and the jumper can be selected from 0 to 10v.
When a system or program reset occurs, the board initializes the automatic scan mode in 64 channels at a rate of 100 KHZ and all channel gains are initialized to uniform (x1). After the reset operation, the program can choose a timed burst or trigger burst mode, and can modify the block size, buffer size, and channel gain as needed. Channel blocks can be adjusted to 1, 8, 16, 32, or 64 channels, and data buffer sizes can be selected in binary increments from 16 to 1,024 data words. In standard performance mode, the board must be reprogrammed after resetting the scan rate of 50 KHZ must write the value $00F7 to the relative address of $0006. Timed data bursts are controlled by an interval timer, which can provide repeated or single burst intervals of up to 687 seconds. An outbreak can consist of up to six
8 to 1024 channel samples. A data ready flag can be scanned in the middle or end of the data ready flag, and interrupt requests can be generated at the same time as the flag. Interrupts can also be initiated after obtaining a specific number of samples
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