Configuration Dialog Box (D2000/Communication with I/O Devices/Communication Stations)
Communication station - a configuration dialogue box
The editing of all objects in the process D2000 CNF is being performed in the configuration dialogue box, a specific part of which is common for all editable objects, and another part depends on the type of edited object.
The configuration dialogue box of communication stations consists of several parts (tabs), which contain similar parameters. Other tabs depend on the category of particular communication stations.
General properties
Description
A text string describing the communication station. Maximum: 128 characters.
A Dictionary can be used (to open it, press CTRL+L).
Value type
Selection of an object value type. For the communication station, it is St - Station.
Parameters
Communication protocol
The communication protocol specifies the type of station communication protocol. The set of protocols is continuously being extended by new ones. The documentation of individual protocols can be found here. The list of available protocols depends on the category of the line, which is the parent of the station, as well as on the scope of the D2000 licence.
Changing the communication protocol is only partially supported by the D2000 KOM process and may require a restart of this process to apply the changes properly. The recommended alternative (which does not require a restart) is to create a new line (with the correct category), new station(s) and migrate the I/O tags using XML export/XML Import (probably also changing their addresses due to the protocol change).
Line mode
The selection of one of four modes of the communication line. For lines of Serial, "Serial Line Redundant", "Serial System&Line Redundant" and "Moxa IP Serial Library" categories, it is possible to define several sets (up to 4) of serial communication parameters. The value of the Line mode parameter determines which of the sets will be used for communication with this station. This enables having stations with various communication baud rates, parities, etc., using the same physical line.
Enable simulation
If the communication station is in the simulation mode, the values of all I/O Tags related to the given station are simulated. The simulation of real (Ai, Ao) and integer (Ci, Co) values is performed by means of values lying on the sinusoid within the range of 0...100. In the case of binary values (Di, Do), TRUE/FALSE values are alternated randomly.
Invalidate I/O tags when the station is off
If the parameter is checked, the values of I/O tags, the parent of which is the station, will be Invalid when the station is off (the state StOFF). Otherwise, the values of I/O tags are the last values before switching off the station.
Communication control
The communication may be controlled in several ways. Check the Manual option to enable controlling the station via the dialogue box in process D2000 HI. The disabled communication option allows enabling (disabling) the communication in Manual mode. The Control object option enables to select the object that controls the communication if the station is in the automatic mode. The control object must be of Boolean type.
Control object value | Station behaviour |
|---|---|
TRUE | Delay of requests for communication. The requests for output are postponed. |
FALSE | Normal communication without any limits. |
OnError behaviour
A behaviour of the station after an error is determined by the Time filter and Delay after error spin buttons (set in milliseconds). If the station does not communicate, it will pass from the NORMAL state to COMM_ERR (soft error). If the communication is not restored even after the expiration of the time corresponding to the value of the Time filter option, the station goes to HARD_ERR (hard error). The Delay after error parameter determines how long after passing to HARD_ERR there will be no communication with the station.
Protocol parameter
The parameters, dependent on the protocol, determine its behaviour during communication with this station. The parameters should be entered into the input field in the form:
PRM1=value;PRM2=value etc.
PRM1, PRM2 - names of parameters
Gradually, we are moving to a new, clearer and more convenient form of entering communication parameters of the station. If it is not possible to enter data in this field (it is not allowed), see the tab Protocol parameters.
More information about protocol parameters...
Time parameters
Polling parameters
The communication process obtains new values by periodic polling of stations.
Period [Hours:Minutes:Seconds] - definition of the period which determines the acquisition of new values of the station's I/O Tags. The period exactly determines the time of sending the request. The period is defined by Hours:Minutes:Seconds and Offset in seconds. For example, the period 0:1:0 with the offset 5 seconds will cause the polling in every fifth second of each minute.
Delay [Hours:Minutes:Seconds.MilliSeconds] - after executing a request, the time of the next request is calculated by adding the Delay parameter to the current time.
The settings of Delay 0:0:0.000 is forbidden for any other priority than the lower one (0), because there is a possibility that other stations can never use the communication.
Synchronization period
Some communication protocols allow setting the real-time into a device. To enable the real-time setting, check the Enable option and enter the period in the form of Hours:Minutes:Seconds, which determines the time of the next station synchronisation (it works similarly to Delay parameter for polling). If the communication protocol does not support the time synchronisation of the station, the request is ignored.
Polling priority
A priority is assigned to each station. It solves the potential conflicts of access to the communication medium (line) - Polling priority option. For the station, it is possible to define one of the five priority levels:
0 - minimum priority
1
2
3
4 - maximum priority
Use computer time
When using the protocols that support sending the values with the timestamps, the timestamps are to be replaced by the current time of the D2000 system (time of the computer with the running process D2000 KOM).
Note: if the start parameter /F is not set to 0 (and therefore watchdog messages are sent between D2000 Server and D2000 KOM processes), the time of the D2000 Server process is transmitted within periodic watchdog messages. The D2000 KOM process then calculates the difference between the local time and the D2000 Server time and corrects the local timestamps by this difference. That is, it effectively uses the D2000 Server time (and so do other D2000 processes). But it also means that if the time jumps on the computer where D2000 KOM is running (e.g. due to time synchronisation), this fact will be detected by D2000 KOM only after receiving the next watchdog message. Therefore, it is recommended to correct the computer time not in one step, but by gradual approximation (i.e. using NTP clients that support such synchronisation, e.g. Windows Time Synchronizer).
Use monotonic UTC time +
The parameter is implemented only for some of the communication protocols that support timestamps: