Navigation:  Setup >   Modbus Communications

 

 

You can check the communicationsModbus Communications  window to see if data is being received and if the communications port is open.  The most current data should be viewed in the Modbus Setup Form.  This form is only used for modbus error checking and to see if the communications port is open.

 

 

The MODBUS communications shows the receive polling and if the port is still working.

The green dot should be flashing green and white.

The is red when the port is closed.

 

 

EDIT MENU

 

The Edit menu allows you to close and start the communications port,

change the poll interval,

send the transmit data (if any)

start or stop the memo (for troubleshooting).

 

EDIT | CLEAR MEMO

 

This command clears the memo so new data can be added to the memo pad.

 

EDIT | INTERVAL

 

Clicking in a row off the PollTime column sets the interrogation interval.  The poll interval is normally set around 1000 milliseconds or (1 second).  This is the speed the serial port will be updated.  The interval menu item just tells you to click in that column to set the interval.  

 

EDIT | CLOSE COMPORT                

EDIT | OPEN COMPORT

 

You can close or open the communications port at any time with these commands.  The lower communications dot will become red when the communications port is closed.

 

EDIT | SELECT COMPORT

 

Communication Port Setting defaults

 

When you select the Edit | Select ComportSelect Comport  menu, a dialog box will be shown, listing the communication parameters.  Make your selections and press OK.  Pressing OK tries to open the selected port.  The decoder is normally configured for 300 or 9600 baud, 8 data bits, 1 stop bit, and no parity.

 

There are four steps that need to be done to start the communications.

 

1.  Connect your serial cable from the computer to the receiver / decoder.

2.  Configure your port for 300 to 9600 baud, 8 bits, 1 stop bit, and no parity.

3.  Open the serial port from the Set Comm menu.

 

 

 

STATUS DISPLAY (1 DOT at the bottom of the communications program)

 

The program will display the status of the communications port and if you are receiving any data from the master.  If everything is running properly, the communication dot will be flashing between white and green.  If no MODBUS addresses have been assigned, then the top grid will not show any updates.  At least one sensor needs to be assigned for the communications to work properly.  A red dot indicates the port is closed or not operating properly.

 

 

 

Setting the Poll Interval

 

The Poll IntervalPoll Interval  can be adjusted for priority polling.  Click on a row in the PollTime Column to change the poll interval (in milliseconds, i.e. 1000 Msecs = 1 second).  Try to make the poll intervals multiples of the lowest time interval.

 

If row one is set to 1000 Msecs and row two is set to 10000 Msecs, row one will be polled ten times before row two is polled.  The system could have alarm words in the first poll and slow moving analog information in the second poll.  It may be important to poll for the alarm information more times than the analog data.

 

 

 

Click on a row in the PollTime column to change the poll interval.  Don't enter commas in the number.

 

 

 

Setting Modem Initialization

 

EVENTS can be set up to initialize a Modem connected to the serial port.  The initialization string can be sent when EVENTS starts up or at any time by selecting Modem | Send Initialization Now from the Communications Form.

 

 

Modem menu

Configure a modem initialization string and send it to your modem on start up.

 

 

Simulate menu

(See Simulating Data)