IGSS can communicate with PLC machines using two general methods
- Polled communication, where IGSS sends requests for data to the connected PLC at predetermined intervals (the Scan intervals). All communication properties are set up and managed in IGSS.
- Event-driven communication, where IGSS waits for the PLCs to send data updates to the objects. All communication properties are set up and managed in the PLC machines.
Event-driven communication is dependent on the selected driver properties and must be selected for each node using the driver.
Event- driven communication has been implemented for Siemens S7 TCP/IP protocol driver (Driver ID:72), enabling you to replace the Siemens S7 protocol driver (Driver ID:8), in your configuration with the Siemens S7 TCP/IP protocol driver (Driver ID:72),
Additionally, if you use the Siemens S7 TCP/IP protocol driver (Driver ID:72), you can communicate directly with the PLC machines and do not need to use the Simatic net for communication between IGSS and the PLCs.
By contrast, the Siemens S7 protocol driver (Driver ID:8) requires the Simatic net for communication purposes.
Event-driven communication
Event-driven communication must be enabled for each node using the Siemens S7 TCP/IP protocol driver (Driver ID:72), in order to available for the objects when designing the configuration in the Definition module.
To enable event-driven communication
1. In the IGSS Master, click Design and Setup tab > System Configuration button to open the System Configuration form.
2. In the left pane of the System Configuration form, expand the station which contains the Siemens S7 TCP/IP protocol driver.
3. Expand the driver and interface folders and select the node you want to use event-driven communication for.
4. In the right pane of the System Configuration form, click the Advanced connection properties button on the Node properties tab to open the Connection Properties form
5. In the Connection Properties form:
- In the S7 SAP field, enter the relevant SAP values as defined in the PLC
- In the PC SAP field, enter the relevant SAP values as defined in the PLC
- In the IP address field, enter the IP address of the PC to be used, if the PC has multiple IP addresses.
- Select the Use event driven communication messages check box.
6. Click the OK button to close the Connection Properties form
7. In the System Configuration form, repeat the step for all nodes you want to enable event-driven communication for.
8. Click File > Save project to save the configuration and then close the System Configuration form.
Datablock and node numbers
When using Event-driven communication, the Siemens S7 TCP/IP protocol driver (Driver ID:72), can also address datablock numbers beyond 255 and node numbers beyond 255.
The normal limit using Polled communication for the Siemens S7 TCP/IP protocol driver (Driver ID: 72 is 32767 datablock numbers and 4095 nodes.
Wait times
If a PLC is set up as a Dialup node and therefore is not in constant communication with IGSS, you can define a time interval for IGSS to listen for scan requests from the PLC to trigger IGSS to scan all changed IGSS object data from the PLC The defined time interval is referred to as the waittime in IGSS.
Waittimes enable you to retrieve data from the PLC when the PLC contains data that is ready to be scanned instead of waiting for the next dialup connection from IGSS to the PLC
Defining Waittimes is possible in the following drivers;
- Siemens S7 TCP/IP protocol driver (Driver ID:72)
- MJK 795 Comli TP6000 radio protocol driver ( DriverID 10),
- General Comli 31 protocol driver ( DriverID 13),
- General Comli TCP protocol driver ( DriverID 75),
- Orum & Jensen PS4 Protocol Driver ( DriverID 75),
- Siemens S7 TeleService adapter interface driver (DriverID 37)
- MODBUS/GPRS driver (DriverID 81)
You must set up Waittime interval and specify the number of milliseconds the driver is to wait before checking for messages from the PLC.
To define the Waittime interval
1. In the IGSS Master, click Design and Setup tab > System Configuration button to open the System Configuration form.
2. In the left pane of the System Configuration form, expand the station which contains the Siemens S7 TCP/IP protocol driver.
3. Expand the driver and interface folders and select the node you want to define the waititme interval for.
4. In the right pane of the System Configuration form, click the Advanced connection properties button on the Node properties tab to open the Connection Properties form.
5. In the Connection Properties form:
- Select the Waittime before listen in mS: check box
- In the field next to the Waittime before listen in mS: check box, specify the number of milliseconds the driver is to wait before checking for PLC messages.
6. Click the OK button to close the Connection properties form
7. In the System Configuration form, repeat the step for all nodes you want to define Waittime intervals for.
8. Click File > Save project to save the configuration and then close the System Configuration form.
Note
When using waittimes for the Siemens S7 TCP/IP protocol driver (Driver ID:72), the driver will not actively scan records and output when waiting for PLC messages. Any defined scan intervals for the driver will be executed after the defined waittime has expired unless a message from the PLC is received.
When troubleshooting the driver, the Waittime interval is called Notify Inbound Call in the Driver log.
Switching nodes and drivers for objects
You can switch objects from nodes using Siemens S7 protocol driver (Driver ID:8) to nodes using the Siemens S7 TCP/IP protocol driver (Driver ID:72) by changing the node and/or driver ID in the Edit Mapping tab on the Object Properties form in the Definition module.
You can also use the Property Table View form to find and switch the drivers and nodes for multiple objects.
Updates only
The new Siemens S7 TCP/IP protocol driver (Driver ID:72) event-driven communication feature is only available for IGSS 11 after you have updated your IGSS Installation.