5 - 12 VM600 MPS hardware manual (standard version) MAMPS-HW/E
Edition 17 - February 2018
System self-checks
AMC8 / IOC8T CARD PAIR
In practice, it can take up to 350 ms (“confirmation time” + “response time”) after an input
signal goes outside the configured OK levels before it is confirmed and acted upon in a
VM600 system as an OK System failure.
When there is an OK System failure on an AMC8 card:
• For the channel in question, the corresponding status indicator (LED) on the panel of the
card blinks green and an OK level alarm (corresponding to the individual
Global Channel OK bit) is signalled.
For example, this can be used to switch a relay on the IOC4T or RLC16 card.
NOTE: Any alarms (A+, D+ and so on) associated with the corresponding monitoring
channel are not inhibited, but remain active.
The following types of monitoring can be performed:
1- RTD devices:
Detection of open circuits and short circuits.
2- Thermocouples:
Detection of open circuits.
3- Voltage-based and current-based signals:
Detection of open circuits and short circuits.
5.8.2 Built-in self test (BIST)
The AMC8 and IOC8T feature built-in self test (BIST) circuitry which provides information
about the operational state of the system. There are basically three types:
1- Global Board BIST
This tests the IOC as a whole and includes a logic watchdog.
2- Channel BIST
This checks each channel to establish whether:
• The shield (S) terminal is incorrectly connected to the sensor (S) terminal
• The linear regulator voltage is correct
• The DC-DC output voltage is correct.
3- Sensor-Specific BIST
Depending on whether a thermocouple, RTD device, voltage-based sensor or
current-based sensor is connected, performs various tests such as:
• Current source checks
• Line checks (to monitor for broken lines)
• Line resistance mismatch (for 3-wire RTD measurements)
• Correct setting of jumper J805.
Errors detected by the BIST are used to set flags that can then be used by the VM600 MPS
software to switch relays and so on.
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