Technical data

A-B SuperBridge Technical Reference

INTRODUCTION

SuperBridge (SB) is a software application that provides two-way communications between

Merrick MC²/MC³ controllers (MCs) and the Allen-Bradley (A-B) communication networks Data

Highway Plus (DH+) and Data Highway 485 (DH485). Serial communication (DF1) between

SuperBridge and a PLC is also supported. Status and variables in MCs will appear on the A-B

networks as integer and floating point files in a PLC-5 or SLC500.

SB will run on an industrially hardened personal computer compatible platform (PC), such as the

Allen-Bradley 1771-DSX2 or 1771-EIP Information Processor, under MS-DOS. Connectivity to

the DH+ network requires the addition of a DH+ communication adapter board or PC card. Up to

128 MC² controllers can be connected to one SB. On the DH+ network, SuperBridge will support

PLC-2 and PLC-5 type DH+ unsolicited messages, such as Typed Read and Write, Word Range

Read and Write, and Read-Modify-Write. In addition, MC data can be automatically exchanged

with one or more PLC-5’s and SLC5/04’s on DH+ along with supporting multiple DH485

compatible SLC500’s over the DH485 network.

This concept is far superior to the traditional method of Allen-Bradley connectivity (1771 Remote

I/O), where the MCs have to mimic an existing Allen-Bradley I/O device, and an Allen-Bradley

PLC has to be present.

PLC connectivity

The ladder programmer can access MC data in two different ways:

• Copy data to PLC. SuperBridge maintains MC data in one or more PLCs. This imposes

minimal burden on the ladder programmer and PLC memory resources. Files are

continuously updated in the PLCs by the SuperBridge with MC general status, status of

digital inputs and outputs, feedrates, totals, alarms and other parameters. The ladder

programmer can access an MC² keyboard and tag specific data items for monitoring and

manipulation. The MCs are completely accessible to the PLC. This also means that the PLC

can act as an advanced version of MasterSet and as a sophisticated sub-system to weighing

controllers, all at the same time.

• Unsolicited messages. The PLC requests MC data from SB. This imposes minimal burden

on the Data Highway communications bandwidth and on the PLC performance. The ladder

programmer creates message rungs to read or write data to or from SB. This method gives

the same level of control as does the copy method above, but the ladder logic programming

effort is greater. For very large systems, this method has an advantage.

It is also possible to use a combination of the two methods.

Control Room software connectivity

Most modern control room or on-line QA monitoring software packages (MMIs) such as Rockwell

Software’s RSView, WinView and WinLinx, and Intellution’s Fix Dmacs for Windows support A-B

connectivity over DH+. This support is available regardless of the presence of an Allen-Bradley

PLC system. The MMI accesses MC data just as any PLC data, normally using the “Unsolicited

messages” method described above. This makes a MC/SB installation open to almost all

modern, powerful control and QA systems. For older MMIs, SB can also impersonate a PLC-2.

MC Controllers connectivity

Up to 128 MC² or MC³ controllers can be connected to a SB, using up to four RS-485, four-wire

connections. MC² controllers must be equipped with a serial port option. A serial port can easily

be added to an existing controller. Some older software versions of the MC² controller must be