DL3000-CMX
DH+ to Modbus

Note: The DL3000-CMX has now been replaced by the DL3500-DH+/Modbus

The DataLink DL3000-CMX contains both Modbus Master and Modbus Slave protocols. When selected for Master mode the DataLink is a Modbus network "Master". It enables PLCs (or smart devices such as PCs) on an Allen-Bradley Data Highway Plus network to initiate a Read/Write transfer of up to 100 registers or 1600 coils to Modbus network slave devices. The DataLink supports Modbus commands 01, 02, 03, 04, 05, 06, 08, 15, and 16, and provides an RS232 serial interface to Modbus with optional RS422/RS485 connections available at additional cost.

The DL3000-CMX (Master) is a Modbus Master and responds to commands from any PLC-5 on the DH+ network, translates them to Modbus format and transmits them to any Modbus slave device on the Modbus network. A Modicon BM85 would allow PLC-5 commands to be sent to Modicon PLCs on Modbus Plus.

Communications between the DataLink and Modbus slaves are initiated from a station on DH+. The DataLink must be the only Master on the Modbus network and does not require a Modbus address. The DH+ network side of the DataLink unit is an active station on the DH+ and requires a unique DH+ address. DataLinks will automatically accept message instructions from PLCs, SLCs, or intelligent devices on DH+ such as PCs running HMI/GUI software.

The -CMX has been enhanced to enable the use of PLC-3 commands as well as PLC-5 commands but the addressing capability is dependent on the PLC type, DH+ message command set, and PLC programming software used. When the DL3000-CMX receives a message over DH+, the Destination Data Table Address (DDTA) field is converted to the corresponding Modbus command, Slave number, and Data address. Please contact us to find out if the DL2000 is suitable for your application.

Operation:

The DataLink receives a command on its DH+ network channel, converts it to the appropriate Modbus command, and sends it out on the asynchronous RS232C Modbus channel to the addressed Modbus slave device. The Modbus slave response is received by the DataLink Master, converted into the corresponding DH+ response and directed back to the originating DH+ station.

When the DataLink receives a PLC-3 / PLC-5 Word Range Read / Write or a PLC-5 Typed Read / Write message command addressed to its DH+ station number, it automatically interprets its Destination Data Table Address and translates it to the appropriate Modbus command and address.