Meggitt vibro-meter SpeedSys300 ODS301, User Manual

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Document reference MAODS301/E USER MANUAL
Edition 4 - May 2022 SpeedSys300 ODS301 overspeed detection system
D - 9
I am seeing a “Slave communication error” message. What should I check?
APPENDIX D: FREQUENTLY ASKED QUESTIONS (FAQ)
D.7 I am seeing a “Slave communication error” message. What should I
check?
The SpeedSys300 ODS301 module uses two processors (microcontrollers) that mutually
monitor each other (the “Duotec” system). Accordingly, the SpeedSys300 ODS301 module’s
two processors (master and slave) are constantly communicating with one another in order
to ensure the correct operation of the module.
If there is any issue with this inter-processor communication, then the module will detect this
as a problem (error) and put the module into its safe state. In addition:
•
On the front panel of the SpeedSys300 ODS301 module, the Error LED will show red.
• On the Device status tab in the SpeedSys300 software, the Error status will display a
“Slave communication error” message (Error code 00000400).
The most likely reason for a Slave communication error message is a high voltage or current
being detected by the module on a sensor input channel, which in turn triggers the Ex (ATEX)
circuit safety, ultimately resulting in the Slave communication error message.
It is therefore recommended to check the appropriate sensor input channel before clearing
(resetting) this error and continuing.
D.8 I am seeing a “Relays PST failed” message. What should I check?
The SpeedSys300 ODS301 module’s self-monitoring and diagnostics (BIST) periodically
runs tests on its relays, known as partial stroke test (PSTs), in order to ensure that they
continue to operate as expected (see
1.1.2 SIL safety ).
If there is any issue with these relay tests, then the SpeedSys300 ODS301 module will detect
this as a problem (error) and put the module into its safe state. In addition:
•
On the front panel of the SpeedSys300 ODS301 module, the Error LED will show red.
• On the Device status tab in the SpeedSys300 software, the Error status will display a
“Relays PST failed” message (Error code 00020000).
In fact, the most likely reason for a Relays PST failed message is actually incorrect grounding
of the SpeedSys300 ODS301 module itself. For example, if the module is not grounded
correctly, a laptop using a switching power supply (floating) that is connected to the USB port
of the module could raise the module’s DC power supply internally (also floating if incorrectly
grounded), ultimately resulting in the Relays PST failed message or other electrical problem.
In general, correct grounding of a SpeedSys300 ODS301 module requires the following
connections:
•
An earth/ground connection between the “instrument earth / GND” (IE ) of the
module’s power supply connectors (PSU x, see Table 2-7 and Table 2-8 ) and the
protective earth (PE) of the power supply or supplies to the module.
• A ground connection between the “intrinsically safe earth / GND” (IS) of the module’s
sensor input connector used (3-WIRE VOLTAGE or 2-WIRE CURRENT, see
Table 2-4
or Table 2-5 ), if applicable, and the “instrument earth / GND” (IE ) of the module.
See also 3.2.2 Power supply , 3.2.3 Grounding and 3.2.4 Shielding for further information
on the power supply, grounding and shielding requirements.
It is therefore recommended to check that the power supply, grounding and shielding are all
in accordance with the recommendations given in this manual before clearing (resetting) this
error and continuing.