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Hytec Electronics Ltd. |
Dual Knob Unit Mark II
Introduction
The primary purpose of this unit is to provide manual control of two computer variables in a control room environment. A typical application would comprise a DEC VAX computer running a control system application, such as Hytec’s VSYSTEM, with its serial (or optional Ethernet) ports connected to knob units to allow parameters to be controlled manually. A software driver in the host provides the connection and the application is able to link a knob to any chosen variable and also vary the ’gain’ of that control. In a similar way, switches and LED indicators on the knob unit can be functionally assigned to produce the desired control functions.
Description
The unit is a 2U high rack–mount assembly, which can also be free standing on a desk. It is very similar to the older original Hytec Knob Unit, catalogue number 5770, with several important improvements:–
Operation
When the unit is switched on, it will enter Normal operating mode unless one of the front panel push–buttons is held down while the self–test is performed. In this case, the unit enters diagnostic mode and various tests and adjustments can be made using a menu on the LCD display and the push–buttons to select items. These same functions are available through the rear panel Diagnostic serial port. In Normal mode, the unit tests the main serial port and reports on the presence and correct operation of either or both on the LCD display and then waits for messages from the host. These messages use the same format as those on the original Knob Unit and allow the user to set–up and write data to the LCD screen, read or write the counters for each knob and read the front panel push–buttons and write their associated LEDs. There is also a miniature sounder, which the host can use to alert the operator. The firmware monitors the counters for each rotary encoder every 10 milliseconds and if the value has changed by more than a value pre–set by the host it will send a message reporting the movement.
Controls
Rotary front panel controls are provided for Backlight Intensity, LED Brightness, LCD Contrast and Sounder Volume. These controls can be either recessed screwdriver adjustments or normal control knobs. A RESET button for the microprocessor is provided, as well as a Backlight ON/OFF button switch.
Specification
Main Serial Port
Single–ended RS232/423 via 25–way Cannon plug or 6–watt MMJ connector (standard DEC);
baud rate up to 38,400 bits per second; data format: data bits, stop bits, parity etc. all controllable
through firmware set–up in diagnostic mode with parameters held in battery–backed RAM.
Internal DIP switches set default formats for initialisation. Optional differential RS422
connection by 25–way Cannon connector. All lines protected against over–voltage.
Diagnostic Serial Port
Single–ended RS232/423 via 9–way Cannon socket (as ECC1365 CAMAC Crate Controller);
set–up features as for the main serial port.
Ethernet Port (Optional)
Thin–wire (BNC) or Thick–wire (15–way Cannon AUI connector) connections for standard 10Mbps Ethernet. Optionally, the Thin–wire port can be replaced by a Twisted–pair link through an MMJ connector. TCP/IP and LLC2/3 protocols are used, as in the ECC. The Ethernet address of the unit is set on switches internally, which are read at power–up. Each Knob Unit also has a “Unit Number” set on a rear–panel rotary switch. This has a similar function to the crate address used on the Ethernet Crate Controller, allowing the host software to refer to a unit or crate number instead of its associated Ethernet address.
AC Line Input and Power Supply
Standard IEC mains inlet, switched, fused and filtered. Auto–ranging power supply accepting 90–264V AC, 47–440Hz. The power supply is protected internally against electrical and thermal overloads. All DC power lines are fused where they enter the main circuit board. Total power consumption: 25 watts maximum, convection cooling.
| Hytec Electronics Ltd Post : 5 Cradock Road, Reading, Berkshire, RG2 0JT, England. Phone : +44 (0)118 9757770 Fax : +44 (0)118 9757566 |