1785-V40B

The Allen-Bradley 1785-V40B is a PLC-5 Series Programmable Logic Controller. VMEbus is a computer bus standard, which was developed for the Motorola 68000 line of CPUs, now it is used for a variety of applications. The 1785-V40B processor is part of a line of enhanced PLC-5 processors. 1785-V40B has the same basic features as the enhanced PLC-5 processors PLC-5/40 and at the same time, 1785-V40B is also compliant with the C.1.  VMEbus specification 1785-V40B can be directly inserted in VMEbus system and use embedded VMEbus system communication interface 1785-V40B can communicate with other VMEbus CPU modules. Through the VMEbus communication backbone, the 1785-V40B can interact with VMEbus I/O modules. 1785-V40B does not have an EEPROM memory module. User memory for 1785-V40B is 48,000 words with a limit of 32,000 words per data-table file. The total number of I/O that can be addressed by 1785-V40B is 1920. 1920 of those I/O can be input and 1920 can be output. The maximum number of analog I/O is also 1920. Program scan time for 1785-V40B is 0.5 ms per 1000 words (bit logic) and 2 ms per 1000 word (typical). I/O scan time for 1785-V40B is 0.5 ms for extended local I/O, and 10 ms per rack at speed of 57.6 kbps, and 7 ms per rack for a speed of 115.2 kbps, and 3 ms per rack at speed 230 kbps. Transmission rates supported by 1785-V40B are as follows: 57.6 kbps, 115.2 kbps, or 230 kbps. 1785-V40B has 4 ports that can be used either as DH+ or remote I/O port. Up to 15 I/O racks can be connected to a processor. 60 I/O chassis is the maximum number of chassis that can be connected remotely to a processor. It is not possible to connect any I/O chassis as extended local chassis. 1785-V40B has one RS-232 port.

On the front of 1785-V40B processor, one can find few communication channels. Channel 0 is 25-pin D-shell connector which integrates optically coupled serial port that supports EIA RS-232C and ASCII or DF1 protocol. Channels 1A, 1B, 2A, and 2B each are 3 pin connectors with user configurable ports that support scanner, adapter, and Data Highway Plus (DH+) communication modes. The programming terminal which is 8-pin mini-DIN connector (2 - connectors) is used as a programming terminal connector. The same ladder programming idea can be used both for enhanced PLC-5/40 processor and for 1785-V40B. Programs are run with the same scan time. In addition to the normal features of series PLC-5/40, 1785-V40B has some other features. In 1785-V40B supports a special data file called "VME status file" that can be defined; this file gives ladder programs the ability to control and monitor certain VMEbus information. Ladder MSG instruction set is enlarged with functions that allow ladder programs to perform VMEbus data transfers and generate VMEbus interrupts. When installed in the 6U VMEbus chassis, the 1785-V40B occupies 2 slots.  For programming and monitoring of 1786-V40B, one can use one of following methods: using a DH+ link, serial communication - using channel 0, or a VMEbus backplane connection. Each of these methods needs adequate hardware on PC stations.