Watchdog Timer, External Reset | Remote Technologies RPC-320

WATCHDOG TIMER

SECTION 11

DESCRIPTION

The watchdog timer is used to reset the RPC -320 if the program or CPU "crashes" . The time r is built into the 80C320 CP U. Timed access requirem ents built into the CPU make it high ly unlikely an er rant pr ocessor would cancel a watchdog timer .

The watchdog should not be used in loops which do not end quickly or ar e of indetermina te duration unless a WDOG command is included. An example of an indeterminate loop is one that waits for a port condition to change.

The timer is set by executing a WDOG n command. n is 0, 1, or 2. 0 turns off the timer. 1 sets the watch dog time to 380 ms while 2 sets it to 2.8 seconds. Executing WDO G by itself resets the timer. WD OG must be executed pe riodically to p revent a reset.

When the watchdog times out, a softwar e reset is

perfor med. The effe ct is lines at J3 do not ch ange as in a power-up or har dware reset. Lines at P6, display, and keypad port ar e reset to power -up conditions.

EXTERNAL RESET

The card is reset externally by mom entarily shorting W10[1- 2]. R eset is also achiev ed by shor ting W10-2 to ground . Maintain this short for at least 10 ms . The card will then reset for abo ut 350 ms.

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Remote Technologies RPC-320 manual Watchdog Timer, External Reset

Contents

Trademarks REVRevision Table of Contents Sect ION 13 Multi Mode Counter Description Sect ION 11 Watchdog Timer DescriptionExternal Reset Interrupt Characteristics Software Revision History Manual Organization OverviewSection Description Technical Support Symbols and Term inology System layout Overview Section Introduction Operating PrecautionsEquipment Uploading and Downloading Programs Using a PCUsing a Terminal First Time Operation Editing programs and program ming hints Troubleshooting Where to GO from Here W3 autorun jumper Saving ProgramsSaving a Program Eprom Changing Eprom Size AutorunningPreventing Autorun Loading a Program Bsave CommandsAlternate Eproms Bload COM0 Serial Port Serial PortsCOM1 Serial Port RS-422/485 Operating Information Serial Ports SectionRS-422/485 Termination network Two wire RS-485 Accessing Serial BuffersMultidrop Network Disabling CONTROL-C Accessing COM0 and COM1Serial Port PIN OUT RXD CTS Changing Memory Battery BackupChecking the battery RAM Memory Storing Variables in RAM Reserved Memory Block Data Transfer Assembly Language Interface Digital I/O Ports Digital and Opto PortsDigital Por t J3 Optically Isolated Input Digital I/O CommandsDigital Port P6 High Current Port L8 High Current Output Interfacing Digital I/O to an opto-module rack Interfacing to switches and other devicesDigital I/ O prog ramm ing exam ple Ls e Width Modulation PWM Conne ctor pin ou t J3 Digital and Opto Ports Section Line B Config LineCount Line Date Setting Date and TimeM E Section Writing to the Display Connecting DisplaysProgramming Example Display Types Display Connector PIN OUT Program explanation Keypad Port Keypad Port PIN OUT J5 Overvoltage conditions Connecting Analog InputsAnalog Input Initialization Examples u sing CON FIG AIN Differential ModeAcquiring Analog Data Noise Notes Temperature Measurement Analog Input Section Measuring Higher Voltages Data logging on a timer tick Amplifiers Converting Analog MeasurementsMeasuring 4-20 mA current loops Calibration External Reset Watchdog Timer Optically Isolated Interrupt Interrupt CharacteristicsProgram Example Optically isolated and TTL interrup ts Gate ProgrammingGND Load COU NT0 Further Power Reduction Power Management Program Examp le Power Management Section Technical Information Electrical Specifications Bank Mechanical SpecificationsMemory and I/O Bank MAP Jumper Descriptions