Novatek-electro RS-485 Operating Manual page 30

2.1. META Section
It contains the general information about the file and settings for its execution, and is responsible for the
particularities of the program cycle fulfillment (the so-called "updates"), including the frequency of updates. Lines in
it do not have numbering, instead of index is "*". Each line has the following format:
* <modifier type> <argument>
The types of the arguments are the following:

<int> - 32-bit signed integer

<uchar> - 8-bit unsigned integer

<ushort> - 16-bit unsigned integer
Table C.2 – Types of modifiers
PROTOCOLVERSION
<int>
UPDATE <int>
UPDATEDIVISOR
<int>
PARAMACTUAL
<ushort>
PARAMRETRIES
<uchar>
PARAMTIMEOUT
<int>
PARAMLOADRATIO
<uchar>
EM-481
Version of the file: It prevents the processing of files with outdated firmware EM-481.
The version described in this document is 8.
Frequency of the program cycle fulfillment (update rate) in seconds: Every cycle
has the reading of parameters, calculation of variables values, defining operation
conditions and implementation of response to these conditions. The frequency
determines only the approximate time of the cycle restart. If during the task execution
the time of the new update (this or another task) will be skipped, this new update will
be postponed until the end of the running cycle. If one or more updates are missed for
the deferred update, these additional updates will not be performed. The minimum
value is 1 second. UPDATEDIVISOR modifier should be used for the higher speeds.
By default, if a modifier is not specified, it equals to 60.
Updating rate divisor allows you to speed up the updating rate. If the divisor is 0,
update cycles are performed with an accuracy of not more than 1 second. For other
values, the accuracy is not more than 0.002 s, with the resulting frequency equal to the
value of the UPDATE / UPDATE DIVISOR fraction, cannot be more than 60 s or less
than 0.002 s. Practical limiting speed, as a rule, is less. The speed is significantly
reduced when using SMS and parameters in the task file, which are accessed through
RS-485 and GSM interfaces.
By default, if no modifier is specified, it is 0.
Frequency of reading the parameters in seconds: It allows optimizing the number of
readings of parameters. At the moment of the updating the parameter it is checked
how many seconds ago it was read last time, and if this time is not more than the value
PARAMACTUAL, then upgrade option will not be read and the last read value of the
parameter will be accepted as current one. Thus, if the total program consists of
several files, reading the same parameters, the number of readings of these
parameters and the excessive load on the communication channels can be reduced.
For the value 0 – with each update the parameter values will be read again.
By default, if a modifier is not specified, it equals to 0.
Number of times to repeat reading in case of error: The value 0 for the
programming cycle there will not be more than one attempt to read the parameter. For
1 – it will be made up to two attempts to read, etc. Calculations and reaction to
conditions can be performed even without a successful reading of all parameters, if
they have sufficient known data.
By default, if a modifier is not specified, it equals to 0.
Time of waiting for response to MODBUS query in milliseconds: It is used if in the
settings of EM-481 the total timeout MODBUS is more than frequency of update of this
file, or if the exception code generation is disabled if no MODBUS response.
By default, if a modifier is not specified, it equals to 1000.
Maximum load of RS-485 channel, in percent: After each query a delay is added,
depending on the waiting time of the last response that allows other clients to send
queries and receive responses. A value of 100 generates the minimum possible delays
(it is not recommended). A value of 50 means a delay equal to the time of waiting for a
response. A value of 25 means a delay of 3 times exceeding the response time.
By default, if a modifier is not specified, it equals to 25.
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