Measurement Computing CB-7000 Utilities - Manual (Page 30)

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3.3.2 Frequent Module Reset Troubleshooting
If the user ’s module has been reset frequently, it may be occur ring because of the following
reasons:
1. Noise levels are too high.
The 7000 series modules are designed for industrial applications. They can be used in a harsh
environment. There is often high electrical noises or RF energy transients in such an environment.
Therefore, the module may go down if these noise sources is too high.
The user can improve the stability and r eliability of applications by reducing noise after the
module has been reset. The Power-On value may be not appr opriate or may even be dangerous
for the user’s application. Thus, the user must send the desired output value again.
Table 3-1. Comparison of Host Watchdog and Module Watchdog
Host Watchdog Module Watchdog
Software or
Hardware Software Watchdog
Built in firmware Hardware Watchdog
Circuit in module
Purpose Monitor the Host PC
Use in all output modules Monitor the Module;
Used in all modules
When to occurs Host is down
Communication line is broken Module is hung
Noise is too high
What to do Module go to safe state
Module status S = 0x04
Module’s output go to safe value
All output command are ignored. Reset the Module
Module Reset status S = 1
Module’s output go to PowerOn
value
CLEAR module-
status
~AA1
S is set to 0
READ module-status ~AA0
S = 4
Î Host is down
S = 0 Î Host is OK
READ and RESET
module-reset –status $AA5
S = 1
Î Module Reset
S = 0 Î Not reset
Setup steps Setup the safe value
Setup the timer interval value of
Host Watchdog and en able the
Host Watchdog Setup the PowerOn value
Send “Host is OK” ~**
Send this command to modules
before timeout intervals expired of
Host Watchdog’s timer.