ABB S800 I/O, Manual

Page: 96 / 176

AI895 Section 3 Run-time Operation
96 3BSE027630-600 B
– Operations in progress
– Hardware faults
– Instruments scan faults and status
– Instruments communication error bits
– Instruments status bits
See I/O Module Status area for more information.
• Flush completed delayed response

This function will delete the response that is stored in the buffer. If the DTM is
in a lock situation when the I/O module always response busy then this
function can be used to flush the HART response buffer.
• Read gateway parameters

This function will read gateway parameters for the module. These are:
– Number of instruments in list
– Number of instruments scanned
– Delayed response, primary master
– Scan enabled
– Number of retries for busy response
– Number of retries for error response
• Enable scan status

This function turns on the scanning.
The scanning function is implemented to monitor the presence of field
instruments. When the scanning is enabled, all instruments of the instrument
lists are scanned with HART command 1. A different channel every 5s. If an
instrument does not reply the DISAPPEARED and SEARCHING bits related
to that instrument are set, else the SCAN_ENABLED will be set.
For the instrument that is not replying the module begins to scan that
instrument with HART command 0. If there is a reply to command 0, the
module verifies if it comes from the original instrument: