1785-L20B AB
About 1785-L20B
Allen Bradley 1785-L20B is a programmable logic controller (PLC) module. This product is a PLC controller belonging to the traditional PLC5 product series.
The 1785-L20B has multiple embedded communication ports, such as one (1) DH+(fixed), one (1) DH+/remote I/O (adapter or scanner), and one (1) serial port, which can be configured to RS-232, 423, and RS-422A standards. These communication ports support separate configuration and mutually independent functions, and can be used simultaneously to achieve expected functions, such as communicating with compatible partner devices for data exchange, communicating with visualization devices, and interacting with programming workstations.
The embedded memory of 1785-L20B is 16Kwords. This memory is a volatile memory maintained by a lithium battery with catalog number 1770-XYC. This controller supports implementing a distributed I/O architecture through DH+or remote I/O protocols. It can also choose to install an Ethernet interface module for implementing distributed I/O systems on the Ethernet. This controller can install up to twelve (12) remote I/O enclosures.
The 1785-L20B controller supports the installation of Electronic Erasable Programmable Read Only Memory (EEPROM) as a memory backup device. Memory options include 1785-ME16 for 16Kwords, 1785-ME32 for 32Kwords, 1785-ME64 for 64Kwords, and 1785-ME100 for 100Kwords.
The 1785-L20B has a built-in port dedicated to the Data Highway Plus (DH+) communication interface, labeled as channel 1A. It also has one (1) combined port that can be configured as DH+or remote I/O (adapter or scanner), labeled as channel 1B. DH+communication can be used for remote programming and monitoring, creating point-to-point communication networks between other PLC-5 controllers, and communicating with visualization systems. Remote I/O connections are used for real-time data exchange between controllers, I/O operator interfaces, and other devices. In addition, the 1785-L20B controller has a 25 pin connector labeled Channel 0, which is an optically isolated EIA RS232C port. This port supports ASCII and DF1 full duplex, half duplex master, and half duplex slave protocols. The other communication port of the controller includes an 8-pin mini DIN connector labeled Channel 1A. Used as a DH+programming terminal in parallel with channel 1A.
