1785-V80B

The Allen-Bradley 1785-V80B is a PLC-5 Series Programmable Logic Controller.

The 1785-V80B processor belongs to a series of PLC-5 processors. This processor has the same instruction set as the enhanced PLC-5 processors PLC-5/80. Additionally, the 1785-V80B is also compliant with the C.1 VMEbus specification. That means that the 1785-V80B processor can be connected directly to a VMEbus system bus, and that 1785-V80B can be used with other VMEbus CPU modules. 1785-V80B can interface with VMEbus I/O modules through a VMEbus communication interface. 1785-V80B processors do not use EEPROM memory modules.

1785-V80B has a memory of up to 100,000 words with a limit of 32,000 words per data table file. The 1785-V80B can address total I/O of 2944, and those I/O can be arranged complementary as 2944 of them are input and 2955 are output I/O.  2944 analog I/O can be addressed by 1785-V80B.

1785-V80B has program scan time of either 0.5 ms per 1000 words with bit logic, or 2 ms per 1000 words which is typical. The extended local I/O scan time is 0.5 ms, and it is 10 ms per rack for transmission rate 57.6 kbps, and 7ms for 115.2 kbps and 3 ms for 230 kbps.

The following transmission rates are available for 1785-V80B: 57.6 kbps, 115.2 kbps, or 230 kbps.

The 1785-V80B processor has 4 ports that can be configured either as DH+ or remote I/O ports, but there is no port for extended local I/O ports. The maximum number of I/O racks that can be connected to 1785-V80B is 23. The maximum number of I/O chassis that can be connected remotely is 92, and it is not possible to connect I/O chassis as extended local. This processor has one RS232 port.

On the front panel of the 1785-V80B there is following communication channels: 0, 1A, 1B, 2A, and 2B.

Channel 0 has a 25-pin D-shell connector. It is an Optically coupled serial port which supports EIA RS-232C and supports ASCII or DF1 protocol. Channels 1A, 1B, 2A, and 2B each have a 3-pin connector. It is has user configurable ports that support scanner, adapter, and Data Highway Plus (DH+) communication modes.

The programming terminal is equipped with an 8-pin mini-DIN connector (2 - connectors) and used for programming purposes.

Ladder programs from enhanced PLC-5/40 processor can run in the 1785-V80B with the same scan time. 1785-V80B has few features that are not presented in other enhanced PLC-5/80 processors. 1785-V80B defines a special data file called "VME status file", this file gives ladder programs the ability to control and monitor certain VMEbus information. Additionally, the Ladder MSG instruction is extended to allow ladder programs to perform VMEbus data transfers and generate VMEbus interrupts.

1786-V80B can be programmed and monitored by use of DH+ link, or use serial communication - using channel 0, or via VMEbus backplane connection.

The VMEbus is a well-known computer bus standard, developed originally for the Motorola 68000 line of CPUs.