The 1785-L30B is an Allen-Bradley controller that belongs to the PLC5 controller family. This controller features 32Kwords user memory, Two (2) DH+/Remote I/O combination ports, configurable for Adapter or Scanner, One (1) serial port which supports RS-232, 423 and RS-422A communication standards.

The 1785-L30B supports a large number of I/O devices. It supports up to 1024 I/O devices which may be composed of any combination of Discrete and analog input and output devices. Additionally, it also supports complementary 1024 input and 1024 output devices.

Aside from the supports for large number of I/O devices, this controller is capable of implementing Remote I/O architecture as it may be connected to a maximum of 28 Remote I/O racks. For implementing Remote I/O architecture, the integrated communication ports such as DH+ and Remote I/O (RIO) channels may be utilized. Additionally, an Ethernet interface module may be added to implement the same architecture over Ethernet network.

The 1785-L30B is installed with a battery that is used by the controller when power is removed from the controller. This battery maintains the user and program data stored within the controller’s user memory. It is assigned with a BATT indicator LED to report the current charge of the battery. For 1785-L530B, the battery can last up to 84 days when powered off at 100% and 150 days if Powered Off at 50% at an operating temperature of 60 Degree Celsius. When the BATT LED energizes, the battery remains operational for 5 days from the first occurrence of the signal. When the battery charge is completely drained, the contents of the user memory is maintained unless power is applied to the controller. It will only be erased when power is removed and battery is drained.

The 1785-L30B has two built-in ports such as channel 1A and channel 1B. These ports are capable of being configured as remote I/O scanners, remote I/O adapters and DH+ communication interfaces. Additionally, the 1785-L30B controller is provided with a 25-pin connector Serial port interface. This serial port supports RS232C standard and configurable for system protocols such as ASCII and DF1. full and half-duplex master protocols and half-duplex slave protocol. An 8-pin mini-DIN connector marked as channel 1A is also provided that supports DH+ connection as well.

The 1785-L30B has several indicators on the front panel used for easy interaction with the user. These indicators are marked as BATT used to display the status of the battery. The indicator marked PROC indicates controller state. The FORCE indicator is used to indicate if I/O forces are enabled. The COMM indicator is linked with channel 0 for reporting communication activity while Channel 1A and 1B both have dedicated status indicator.

The controller has a Three-position key-switch for setting the controller mode. Each position corresponds to one mode of the processors such as Run, PROG and REM. When in RUN mode, the controller executes the program and activates output devices. PROG halts the logic execution and allows controller configuration and programming. REM executes the logic program and allows configuration and programming.

The1785-L30B has 32000 words of memory with a 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. The 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.