The
See
Note
This information is provided for the benefit of customers who have legacy implementations of Modbus communications using the
When setting up your Modbus network, make sure that your Modbus port is different from the port that connects to your
Start
Click Tools > System >
Double-click an item to expand or collapse it.
The buttons available vary depending on the item selected in the tree.
Expand Modbus Network to show “Master Sites” and “Slave Ports”.
Select Master Sites then click Add Site.
Select Ethernet (RTU) then type the following in the appropriate fields:
TCP/IP Address: the TCP/IP address of the Master site or gateway
TCP/IP Port: the TCP/IP port number used to connect to the COM port used by the Modbus network (for example, TCP/IP port 7802 connects to an EtherGate device’s COM2 port).
Click OK.
Note
Do not use 502 for the TCP/IP port. Modbus/TCP packets use the TCP/IP protocol and are sent to this registered port number. At this time, the
Select Master Sites then click Add Site.
Select Serial Site, then set COM Port to the serial port of your computer that you want to assign as your Modbus Master. The
Click OK.
Note
The COM port used to define a Master Site must be different from the COM port used for connecting to
Select the site and expand the tree until the parameters under Settings are displayed. Select the parameter you want to change, and then click Modify <setting> (where <setting> is the setting selected).
Transmit Delay: The amount of time the
Note
For Ethernet sites, specifying too small a value for Transmit Delay may overload the network.
Receive Timeout: The time period the
Note
For Ethernet sites, the protocol used is Modbus RTU which does not identify packets. Therefore, specifying too small a value for Receive Timeout may cause timeouts, which could result in packet mix-up. Specify a value that avoids timeouts.
Baud Rate (serial sites only): The Baud rate used for Modbus communications to serial sites. Supported values are 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200.
Parity (serial sites only): This setting specifies whether or not parity is active (and if it is active, the type of parity; i.e., Odd, Even, Mark, or Space). Parity refers to a technique of checking whether data has been lost or overwritten when it is moved from one place in storage to another, or when transmitted between devices and/or computers.
Stop Bits (serial sites only): The number of stop bits supported by the site. Supported values are a minimum of 1, 1.5 and 2. Stop bits signal the end of a unit of transmission on a serial line.
Data Bits (serial sites only): The number of data bits (i.e., bits that contain information or data) supported by the site. Supported values range from a minimum of 4 and a maximum of 8.
Select the Modbus Master site to which you want to add a Modbus device. Expand the tree to display Settings and Devices. Select Devices, then click Add Device. The Add Modbus Device(s) dialog box appears.
Enter the Name and Unit ID of the Modbus device in the appropriate fields. For Ethernet devices, set Unit ID to 100. The Name must be unique among all the sites serviced by the
Repeat the previous step to add more Modbus devices to the same site. When you have finished connecting all the Modbus devices to that site, click OK.
Note
A Modbus device name must start with a letter, followed by letters, numbers and/or underscores. The Modbus device name must not contain spaces. The supported range for a Modbus device Unit ID is 1 to 247. Do not use “0” (zero) as it is reserved for broadcast messages.
Select the Modbus device you want to rename. Click Rename Device. The Modbus Device Name dialog box appears.
Type the new name, then click OK.
Note
If you rename or delete Modbus devices, all Modbus Export or Modbus Import modules that previously referred to that renamed or deleted Modbus device are mapped to “not_a_valid_device” when you restart the
Select the Modbus device you want to delete.
Click Delete Device then click OK to confirm the deletion.
Tip
If you want to use ION data in your Modbus network, you need to convert the data to Modbus. Use
Expand Modbus Network to display Master Sites and Slave Ports. Select Slave Ports, then click Add COM Port. The Modbus Port/Site dialog box appears.
Set the COM Port to the port you want to use as a Modbus Slave port (this is the port that the Modbus Master uses to read Modbus data from the
Note
The Modbus Slave port must not be set to the same port as any ION or Modbus Master ports.
Expand the COM port you have just added to display Settings.
Expand Settings to show the items below it.
Select Unit ID then click Modify Unit ID. The Modbus Slave Unit ID dialog box appears.
Enter the Modbus Slave device unit ID. Click OK.
If you want to modify the Baud Rate, select Baud Rate then click Modify Baud Rate. Select the new baud rate from the dropdown list, then click OK.
If necessary, configure the Parity, Stop Bits and Data Bits.
Select the port you want to reassign, and then click Rename Port. The Modbus Port/Site dialog box appears.
From the dropdown list, select the port you want to reassign to the Modbus master or slave (see
Note
Deleting a Modbus Master Site also deletes all devices connected to it.
Click on the site or port you want to delete, and then click Delete Port or Delete Site (depending on the item selected).
Click OK to confirm the deletion.
When you have finished using
In order for the changes to take effect, you must stop then restart the
Typically you do not need to change the default
| Global Parameter | Value Range | Description | Notes |
|---|---|---|---|
| Module Update Period | 50 to 1000 ms | The interval at which ION modules inside the |
Frequent module updates contribute to the workstation's processor load. By increasing the Module Update Period, you reduce the number of times a module executes in a given time period. |
| Configuration Saver Period | 10 to 600 seconds | The interval at which the |
Increasing the Configuration Saver Period significantly reduces the processor load if you have a large |
| Client Polling Period | 500 to 300000 ms | The interval at which the |
You can increase the period for less critical |
| Server Polling Period | 200 to 1440000 ms | The interval at which the |
Reducing this value increases the rate at which these responses are sent; however, this can also increase network traffic. |