AB 1756-DHRIO, 1756-DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module

AB 1756-DHRIO, 1756-DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module

Module Overview: The 1756-DHRIO and 1756-DHRIOXT modules support Data Highway Plus (DH+) messaging, Control and Information Protocol (CIP) messaging, and Remote I/O functionality to enable communication between devices on different networks. The modules have a routing table to assist DH+ devices in accessing other networks, and there is no limit to the number of modules per chassis, subject to slot and power supply capacity. The front panel of the module is equipped with a status indicator to show the working status of the module.

Installation Guidelines: Before installing the module, verify the module characteristics, set the network type and node address switches, and install and connect the ControlLogix chassis and power supply. To install, insert the module into the chassis rails and ensure that the backplane connectors are properly connected. When wiring, be careful to disconnect power when connecting or disconnecting communication cables to prevent dangerous electrical arcing. Specific cables are required for different network connections, e.g. 1770 - CD cable for the 1756 - DHRIO module to connect to the DH+ and Belden 89463 cable for the 1756 - DHRIOXT module.

Network communication

DH + Network: The DH + is a wired network that connects devices and supports communication between multiple devices with up to 32 stations on a single link. The network is designed for performance, maintenance, and future expansion, and can be daisy-chained or in a trunk/branch configuration, with cable lengths and termination resistors selected based on communication rates. There are two ways for the modules to communicate in a DH+ network: Local DH+ messaging is used for communication between devices on the same physical link without a complete routing table; Remote DH+ messaging is used for communication between devices on different networks, and requires a configured routing table and a unique link ID.

CIP Messaging: CIP is a communication mechanism for ControlLogix chassis, ControlNet networks, and Ethernet that routes messages through the concept of ‘relative paths’ without the need for a routing table and link IDs. 1756 - CIP is supported on DHRIO and 1756 - DHRIOXT modules, but there is a limit to the number of connections. The 1756 - DHRIO and 1756 - DHRIOXT modules support CIP messaging, but there is a limit to the number of connections, with a maximum of 32 connections per DH+ channel, including a maximum of 5 CIP connections.

Use of programming software: Different controllers and modules require specific programming software, e.g. PLC controllers with RSLinx and RSLogix 5, SLC controllers with RSLinx and RSLogix 500, ControlLogix controllers with RSLinx and Studio 5000 environments. With RSLinx, routing tables can be created and controller slots configured; each software is configured according to the appropriate procedure when sending message commands.

Messaging between controllers: Covers DH+ messaging between PLC-5 and SLC 5/04 controllers, PLC-5 or SLC 5/04 and ControlLogix controllers, ControlLogix and PLC-5 or SLC 5/04 controllers, and ControlLogix controllers. Each of these scenarios requires configuration of module switches, routing tables, and message commands based on the specific application scenario, with some scenarios requiring attention to controller slot settings and message mapping table configuration.

Remote I/O Applications: Remote I/O systems use the 1756-DHRIO or 1756-DHRIOXT modules to control non-local I/O devices. When designing a remote I/O network, follow the network and cable design guidelines for device selection and connection planning. The module acts as a scanner in remote I/O applications, exchanging data with remote I/O adapters and ControlLogix controllers at a rate controlled by setting the Request Packet Interval (RPI), which affects the rate at which the remote I/O scanner status is updated.

Studio 5000 Environment Applications: When using the Studio 5000 environment for Remote I/O and Block Transfer applications, the Remote I/O application adds modules, configures modules and adapters, and downloads projects; the Block Transfer application adds Remote I/O modules and configures the Block Transfer message commands. In the process of configuration, you have to set parameters such as module name, type, baud rate, electronic key, RPI, etc., and pay attention to the relevant settings of adapters and modules.

Troubleshooting and Command Support: You can judge the working status of the module by checking the module status indicators, such as the power indicator, alphanumeric status indicator and channel status indicator. When encountering problems, you can investigate according to the error messages displayed by the indicators. The module supports PCCC commands, such as display back, ID host and status query, read and reset DH+ diagnostic counters, etc. These commands are executed by the module under specific conditions, which can assist debugging and analysing module operation.