This chapter provides an overview of the BASEstar Classic DAS for Modicon programmable controllers. It also briefly describes Modicon programmable controllers and the supported functions for the DAS.

1.1 Description

The DAS for Modicon programmable controllers allows you to access Modicon programmable controllers through BASEstar Classic device connection management capabilities. Device connection management is the device connection/control component of BASEstar Classic for OpenVMS. BASEstar Classic for OpenVMS is software designed to facilitate the integration of manufacturing equipment and applications, accelerate the development of integrated manufacturing systems, and provide an architecture for consistent development of manufacturing applications.

Using the DAS for Modicon programmable controllers, users or applications can perform a variety of device access functions which include: reading and writing data, uploading and downloading, and reading the status of a device.

1.2 Device Communications

The DAS for Modicon programmable controllers consists of two protocol emulators (PE) and three network interfaces (NI). A PE and NI work together to provide device-specific communications for BASEstar Classic device connection management's generic callable services.

The PE translates BASEstar Classic device connection management's generic services into a device-understandable format. The PE also converts device-specific protocol into a BASEstar Classic device connection management format. The NI works directly with a OpenVMS driver to send data to and receive data from plant-floor devices. The NI communicates the requests and data translated by the PE. Figure 1-1 shows how the DAS facilitates communications between BASEstar Classic device connection management and the devices.

The Modicon 584 PE is supported only for use with the Modbus NI. The Modicon 984 PE can be used with any of the supplied NIs.

Figure 1-1 DAS Communications

You can perform only the BASEstar Classic device connection management functions that are supported by a device's PE. These functions can be accessed through BASEstar Classic device connection management's menu system, commands, and callable services.

The DAS for Modicon programmable controllers supports the following BASEstar Classic device connection management functions:

• Start and stop operations on a device
• Upload the contents of a device's memory to an OpenVMS file
• Download an OpenVMS file to a device's memory
• Read data from a specific address in a device's memory
• Write data to a specific address in a device's memory
• Read status of a device

The DAS for Modicon programmable controllers supports a variety of programmable controllers, as shown in Table 1-1.

Table 1-1 Modicon Programmable Controller s

Device	Upload	Download	Start	Stop	Read Data	Write Data	Read Status
Quantum 1	X	X	X	X	X	X	X
984A	X	X	X	X	X	X	X
984B	X	X	X	X	X	X	X
984X	X	X	X	X	X	X	X
584L	X	X	X	X	X	X	X
584M	X	X	X	X	X	X	X

For more information about the supported functions, refer to Chapter 3 of this document.