History Reading; Check Field Calculation; How Get Numbers Of Modbus Communication Objects - ComAp InteliSys NTC Basebox Communications Manual

9.3.4 History reading

It is not possible to read history from more terminals simultaneously. Reading must be started by writing of an
index of requested history record. If the index is not written it is not possible to read neither history header nor
data part of the record. In this case the controller returns an error message. If the terminal writes the index of
requested record, history reading is locked for other terminals (i.e. reading and writing of an index of requested
record, reading of header and data part of the record). It is unlocked 5 seconds after the last history reading.
Locked history is indicated to other terminals by an error message.
Requested history record is stored at the moment of locking in the cache memory and following reading is
performed from this memory.
Note: History reading is not possible in some specific firmware versions. See the concrete firmware version
and its New Feature Lists.

9.4 Check field calculation

The check field allows the receiver to check the validity of the message. The check field value is the Cyclical
Redundancy Check (CRC) based on the polynomial x
preceding the check field.
9.5 How get numbers of Modbus communication
objects
Image 9.1 A part of Cfg Image
(Modbus Register ...) file
IGS-NT Communication Guide
16 15 2
+x +x +1. CRC is counted from all message bytes
Communication objects can be spitted into two
groups:
Communication objects dependent on the
application type (SSB, SPM, SPtM, MEXT,
MINT, ...).
Communication objects independent on the
application type.
Use GenConfig menu command File –> Generate
Cfg Image –> Generate Cfg Image (Comm. Objects
...) and Generate Cfg Image (Modbus Registers
all/used).
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