I/O Drivers

In order for each primary block in the database to receive data, you must connect to your I/O using an I/O driver. The driver you select depends on your process hardware. GE sells drivers for many types of hardware. Contact your GE Sales Representative, or refer to our web site at at https://digitalsupport.ge.com for a list of available drivers.

After you purchase a driver and install it, you can start specifying I/O points you want the current block to use. If the I/O point does not exist, Database Manager starts your I/O driver configuration program so you can add it. Refer to your I/O driver documentation to learn how to add an I/O point to your driver configuration.

iFIX supplies an OPC Client I/O driver, as well as two simulation drivers.

OPC Client Driver

The OPC Client driver provides the interface and communications protocol between OLE for Process Control servers and iFIX.

The OPC Client driver supports the following features:

  • Analog register and digital register database blocks
  • Special addressing for analog output and digital output blocks
  • Text blocks
  • Item property I/O addresses for text blocks
  • Block writes
  • Data arrays
  • Exception-based processing
  • Latched data

Simulation Drivers

You can use the SIM and SM2 to test your chains before you connect to real I/O. The simulation drivers are matrixes of addresses. Database blocks read values from and write values to these addresses. If one block writes to a specific address, other blocks can read the same value from the same address. You can save these values when you save the process database; however, iFIX removes them from memory when SAC starts or you reload the database.

Both drivers have the following in common:

  • Provide a matrix of addresses that database blocks can read from and write to.
  • Support analog and digital database blocks.
  • Support text blocks.

The drivers differ in the following ways:

The SM2 driver...     

The SIM driver...

Provides three independent sets of registers. Analog blocks automatically access the analog registers, digital blocks automatically use the digital registers, and Text blocks automatically access the text registers.

Provides one set of registers shared by both analog, digital, and text blocks.

Changing a register in one set does not change the same register in the other set. For example, if you change the value of the analog register 1000, the value of the digital register 1000 is unchanged.     

Changing an analog register in the SIM driver modifies the register for analog, digital, and text reads. For example, if you change the value of the analog register 1000, you also modify the value of the same digital register.

Provides 20,000 analog, 20,000 16-bit digital registers, and 20,000 text registers.     

Provides 2000 analog and digital registers, a total of 32,000 bits.

Stores analog values in 4-byte (32-bit) floating point registers, numbered 0 to 19999. Incoming values are not scaled.

Stores analog values in 16-bit integer registers, numbered 0 to 2000. Incoming 32-bit values are scaled to 16-bit values (0 - 65535).

Digital values are stored in 16-bit integer registers, numbered 0 to 19999.

Digital values are stored in 16-bit integer registers, numbered 0 to 2000.

Text values are stored in 8-bit registers numbered 0 to 19999. Each register holds one text character for a total of 20,000 bytes of text.     

Text values are stored in the same area as analog and digital values, numbered 0 to 2000.

Provides a register to simulate communication errors.      

Cannot simulate communication errors. However, the SIM driver does provide registers RA through RK and RX through RZ to generate random numbers. For more information, refer to the Using Signal Generation Registers in the SIM Driver section.

Supplies a C API that allows applications to access SM2 analog, digital, and text values.     

Does not support a C API for accessing SIM values.

Supports exception-based processing.     

Does not support exception-based processing.

Supports latched data for Analog Input, Analog Alarm, Digital Input, Digital Alarm and Text blocks when a simulated communication error is enabled.      

Does not support latched data.

Can read and write the individual alarm status of each SM2 register.     

Cannot read and write the individual alarm status of any SIM register.

Does not provide alarm counters.     

Provides alarm counters that show the general alarm state of a SCADA server. For more information, refer to the Using Alarm Counters chapter of the Implementing Alarms and Messages manual.

 

See Also