Peek 2070L Operating Manual - Quality Traffic Systems
Section 6 — Theory of OperationOn receipt of this frame, the watchdog timeout value shall be changedto the value in the message and the “Y” bit set. The response frame bit(Y) shall indicate a '1' if the watchdog has been previously set and a '0'if not.(TEES-2002: Section 184.108.40.206 - Controller Identification)This is a legacy message command / response for FI/O modules withDatakey resident. Upon command, a response frame containing the128 bytes of the Datakey. On NRESET transition to High orimmediately prior to any interrogation of the Datakey, the FI/O shalltest the presence of the Key. If absent, the FI/O Status Bit “K” shall beset and no interrogation shall take place. If an error occurs during theinterrogation, Bit “K” shall be set. If “K” bit set, only the first two bytesshall be returned. The Command Response frames are as follows:(TEES-2002: Section 220.127.116.11 - Module Identification)The FI/O Identification command frame shall be used to request theFI/O Identification value Response of “1” for 2070-2A. The commandand response frames are shown as follows:6.2.5 Display ModuleThe 2070-3B display module provides the 2070L with its physical userinterface, including an LCD screen and dual keypad inputs. The display isattached to the chassis via the chassis’ hinge, and to the chassismotherboard via the chassis’ J1 ribbon cable.58 • Model 2070L Operating Manual
Detailed Systems DescriptionFigure 22 – Display Module block diagramThere are basically four sections of the display module’s operation: the LCDdisplay, the front panel controls, the microcontroller and associated logic,and the connectors. The connectors are comprised of a J1 ribbon cablewhich connects the display module to the chassis (and through that to theCPU and the rest of the controller,) and a front-panel C50S serial connector.The ribbon cable provides two RS485 serial comms channels (SP4 andSP6), several TTL-logic status lines, and power from the chassis. SP4connects to the C50S connector. SP6 provides data flow between the frontpanel microcontroller and the 2070L’s CPU.The microcontroller operates as the ‘brain’ of the display interface, routingdisplay elements to the LCD, keypad inputs to the screen and the CPU, androuting CPU data to the display. The micro reads the status of eight factorypresetlinks that function as the Config for the display, telling the controllerwhat type of LCD and keypad are installed. The micro uses the two memorylocations (EPROM and SRAM) to store its internal application and data to bedisplayed on the LCD. The data is transferred by the micro to memory andto the LCD across a data bus.The LCD is driven by the microcontroller using the data bus and an LCDcontrol channel. The LCD itself has a backlight and a contrast setting. Thecontrast setting is set using the front panel Contrast knob. This contrastknob is connected to a variable resistor that directly controls the LCDsetting, so it is possible to inadvertently turn this all the way down or up andnot be able to read the display. The LCD’s backlight is activated by themicrocontroller whenever the keypad is pressed.Model 2070L Operating Manual • 59
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Contents4.1.3 Environmental .......
ContentsTable of FiguresFigure 1 -
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Section 2 — General Description2.