Specifications

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SLC 500 Programmable Controllers and I/O Modules
1747-ASB Remote I/O Adapter Module
The Remote I/O Adapter module is a single-slot, RIO communication link module. It occupies the first slot (slot 0) of a 1746 remote
chassis, where the SLC processor normally resides. The ASB module acts as a gateway between an SLC 500 remote I/O scanner and the
I/O modules in the 1747-ASB remote and expansion chassis. The ASB module is compatible with all Allen-Bradley RIO scanners.
Features
• Supports 1/2-slot, 1-slot, and 2-slot addressing — Provides efficient image utilization by allowing you to assign the amount of space required.
• Monitor three 7-segment displays - Provides status information and troubleshooting.
1747-DCM Direct Communication Module
The Direct Communication Module (DCM) links the SLC 500 controller to the Allen-Bradley PLC for distributed processing. The DCM acts
as a remote I/O adapter on a remote I/O link. Information is transferred between a local PLC or SLC scanner and a remote 1747-DCM
module during each remote I/O scan. The number of DCMs that a scanner can supervise depends on the number of chassis’s the scanner
supports and the chassis size of the DCM. The SLC 500 modular controllers support multiple DCMs. An important distinction between a
DCM module and an ASB is that a DCM is placed in a chassis with a processor and it does not scan any I/O in the chassis as an ASB does.
Serial Network
The SLC 5/03, 5/04, and 5/05 processors (see pages 8-10) have a serial port which is configurable for RS-232, RS-423,
or RS-422A-compatible serial communication. Use the serial port to connect devices that:
• Communicate using the DF1 protocol, such as modems, communication modules, programming workstations, or
other Encompass partner devices.
• Send and receive ASCII characters, such as ASCII terminals, bar-code readers, and printers.
When configured for system mode, the serial port supports the DF1 protocol. Use system mode to communicate with others devices on
the serial link. You can select a DF1 mode:
• Point to point: communication between a SLC 500 controller and other DF1-compatible devices. In point-to-point mode,
the SLC 500 controller uses DF1 full-duplex protocol.
• DF1 master: control of polling and message transmission between the master and each remote node. In master mode,
the SLC 500 controller uses DF1 half-duplex polled protocol.
• DF1 slave: using the controller as a slave station in a master/slave serial network. In slave mode, the SLC 500 controller
uses DF1 half-duplex protocol.
The serial port (in system mode) also supports supervisory control and data acquisition (SCADA) applications. SCADA systems let you
monitor and control remote functions and processes using serial communication links between master and slave locations.
When configured for user mode, the serial port supports ASCII devices. Use the SLC 500 ASCII instructions to send and receive
information from these devices.