Dewar Monitor System Electronics
Page last updatedNovember 14, 2011
This panel shows the digital inputs for the RIO-47122. Inputs DI0 - DI7 are tied to the CABLE CONNECTED signals that are supplies by the GND of the dewar electronics box's preamp board. That is, the DMS ground signal is tied to the dewar's ground and then a second ground pin on the preamp is looped back to the DMS as the CABLE CONNECTED signal. The INPUT SELECT BITS are BCD inputs from the "SELECT" paddle switch and are used to select a single channel to look at. The "SHOW_TEMP" input is wired to the"PUSH TO HOLD SELECTED CHANNEL" pushbutton and as might be imagined, is used in tandem with the select switches to display and hold the temperature of the selected channel. The "RESET" input is wire to the reset pushbutton on the alarm panel and is used to either reset any current alarms or, if held for 4 seconds, to reset all channels. Finally, the three AUX inputs are wired to the "ALARM IN" connector. At this time, they are not used or looked at by the RIO's program.
The next panel shows the RIO's digital outputs. The first eight outputs drive the green LEDs on the front panel that correspond to the eight dewar channels. These LEDs are on when that channel is active, or dark if not active. Active refers to the channel currently being processed. A third indication is flashing. This occurs when a channel is warming up and has tripped the alarm. The "I'M ALIVE" output drives the "I'M ALIVE" front panel LED. The outputs DO14, DO10, and DO12 each illuminate the LEDs on the alarm panel. These are available for future use.
The eight analog inpusts are used to read the temperatures from any connected dewars. These signals are amplified by an op-amp with a gain of 10 on the EL-5010 board. Once read into the RIO, the appropriate offset and scaling are applied to the input to generate the dewar temperature.
The only RIO analog output currently used is output AO0. This is wired directly to the front panel DVM. As the RIO cycles through its program, the current input's corrected temperature value is sent to the DVM.