32 C4 Manual Rev 7.5.2
The Probe Out of Range Shutdown condition can be cleared by pressing
<START/STOP> in Local or Program mode, by rotation the mode switch on the
front panel to a different position, or by issuing a Device Clear in Remote mode.
3.7 Internal Error Shutdown Conditions
The C4 monitors system health by keeping track of four internal areas; they are:
Processor health Tracked by watchdog timer
Memory condition Checked at startup
Setup parameter integrity Checked continuously
IEEE-488 bus integrity Checked continuously
The first three items, above, are discussed in sub sections below. The IEEE-488
bus controller is automatically reset if a problem is detected. No message to the
user is generated as no data is typically lost in the process.
3.7.1 Watchdog Timer
Should the system become locked due to corruption that causes the processor to
continuously malfunction, an independent watchdog timer will cause a full system
reset. After a watchdog reset, the display will show
res err
When this occurs, the mode switch must be turned to the OFF position, then back
to the desired mode to clear the reset message and continue operation. Internal
memory will be the same as it was when the shutdown condition occurred.
3.7.2 Memory signature checking
Each time the C4 is powered up, the system checks a series of memory signature
bytes to test the integrity of system memory. If the signature bytes are not
correct, the system assumes that memory has been compromised. If this should
occur (a normal event any time a memory chip is replaced) all of system memory
is reinitialized. All program steps for Program mode are reset to their default
values, and all setup parameters are reset to their default values. The display
will show
all res