About 1785-L30B

Programmable controller 1785-L30B is the main part of each enhanced control system based on the Allen Bradley PLC-5 series. The 1785-L30B merges local, extended and remote I/O modules on various types of communication interfaces into one control system suited for various processes. 1785-L30B has two built-in ports. Ports are marked as channel 1A and channel 1B, and both can function as remote I/O scanners, remote I/O adapters and DH+ communication interfaces. DH+ communication can work both for remote programming and monitoring of 1785-L30B, and for creating a peer-to-peer communication network between the other PLC-5 controllers. Remote I/O connection is used for real-time data exchange between the controller and I/O, operator interface, and other devices. On the front panel of the 1785-L30B controller, there is a 25-pin connector marked channel 0. This is an optically isolated EIA RS232C port. Channel 0 supports ASCII and DF1 full and half-duplex master protocols and half-duplex slave protocols. On the front panel, there is a green channel 0 communication indicator light. Near channel 0, there is an 8-pin mini-DIN connector marked as channel 1A, and a DH+ programming terminal connection parallel to it. There are two three-pin connectors that serve as communication ports. These three pin connectors are used for channels 1A and 1B, which can be configured as remote I/O scanners, remote I/O adapters or DH+ communication ports. Both channel 1A and channel 1B on 1785-L30B can function as remote I/O scanners or remote I/O adapter communications. Remote I/O Scanner Mode reads and writes I/O information between a controller and remote I/O device. In this mode, 1785-L30B is a supervisory controller for other controllers that are in adapter mode and remote I/O adapter modules. When channel 1A or 1B is in Remote I/O Adapter Mode, it controls its controller-resident local I/O while communicating with the supervisory controller via a remote link. On the 1785-L30B, the Data Highway Plus (DH+) link can function both on channel 1A and 1B. DH+ communication can be used for data transfer to other PLC-5 controller or other higher-level components of the control system. DH+ link can program multiple PLC-5 controllers. Maximum cable length for DH+ link depends on the transmission rate. It is crucial that all devices on a DH+ link are configured to communicate at the same transmission rate. 1785-L30B has several indicators on the front panel used for easy interaction with the user. Indicators are used for displaying various statuses of the controller. The indicator marked BATT displays the status of the battery. The indicator marked PROC indicates controller current mode, it is green when the controller is in RUN mode, and red when something is wrong. The FORCE indicator is amber when I/O forces are enabled. The COMM indicator is linked with channel 0. It is green when the channel is communicating. Channel 1A and 1B both have dedicated status indicator.

On the front panel of the 1785-L30B, there is a three-position key-switch for selecting controller mode. Each position corresponds to one mode of the processors. RUN mode is used for running controller program, enabling outputs. In RUN Mode, I/O can be forced, and data table values can be edited, and programs can be saved. In RUN Mode, it is impossible to create or delete a program or data file, edit online or change modes of operation via programming software. When the 1785-L30B processor is in Program Mode (PROG position of key switch), outputs are disabled, and ladder files, SFC files or data files can be created, modified and deleted. Download and upload transfers are possible with the memory module, and programs can be saved or restored. In program mode, the 1785-L30B processor does not scan the internal program, and mode of operation cannot be changed with programming software. The 1785-L30B processor’s third mode is the Remote Mode, selected by moving the key switch to the REM position. In this mode, it is possible to choose between the three sub-modes Remote Program, Remote Test, and Remote Run. This selection works via programming software. When the processor is in Remote Run Sub Mode, outputs are enabled, and programs can be saved and restored and edited while operating. Remote Program Sub-Mode is same as Normal Program Mode. While in Remote Test Sub Mode, ladder programs can be executed with outputs disabled, but ladder programs and data files cannot be created or deleted. Programs can be saved, restored and edited while operating. The 1785-L30B has 32000 words of memory, and the controller RAM has battery backup. For program backup, an EEPROM module can be installed in the front panel slot. Various memory module capacities are available. The total number of I/O (including local I/O and universal remote I/O combined) is 1024 any mix, or 1024 inputs and 1024 outputs complementary, meaning that in order to use this much I/O, pairs of modules must have duplicate addresses. The maximum number of analog I/O is 1024. 1785-L30B can utilize a total of 29 I/O chassis, and among them, 28 can be universal remote I/O chassis. The backplane has a current load of 1785-L30B is 2.3 amps at 5 Volts. The 1785-L30B does not have the capability of connecting extended local I/O chassis.