Serial Port Connector
The 15-pin D-connector at the bottom of the module provides the connection to an RS-422/RS-485 serial port. Its port provides a serial connection to the Work Station Interface (WSI) board installed in the programming computer. For applications requiring RS-232 communications, an RS-232 to RS-422 converter (IC690ACC900) or RS-232 to RS422 miniconverter (IC690ACC901) is available.
Note
An RS-422 Isolated Repeater/RS-232 Converter (IC655CCM590) is available for applications requiring ground isolation where a common ground cannot be established between components.
A standard serial COM port version of Logicmaster 90-70 programming software provides logic programming and configuration for the Series 90-70 PLC using the COM1 or COM2 serial port of the programming device (a Work Station Interface board is not needed). Connections for this configuration are made from the programmer's COM1 or COM2 serial port to the converter to the serial port on the Series 90-70 CPU.
Expansion Memory Board
The CPU 780 requires an expansion memory board (see GFK-0837 and GFK-0531C, or later versions), for more information. The expansion memory board uses battery-backed CMOS RAM memory devices for program and data storage. These expansion memory boards are arranged in a 32-bit memory configuration and can only be used on the models 780, 781 and 782 CPUs. Error checking is provided by a CPU checksum routine. Logic program memory is continually error-checked by the CPU as a background task. Memory parity errors are reported to the CPU when they occur.
These expansion memory boards are not compatible with the expansion memory boards used with the models 771 and 772 CPUs or the Programmable Coprocessor Module. Four versions of the 32-bit memory expansion board are available as listed in the table below. These expansion memory boards are installed on the CPU 780 module by mounting them on a connector provided for that purpose. The CMOS RAM memory on the expansion memory boards is backed-up by the Lithium battery mounted on the CPU module on which the boards are installed.
| Table 3. | Expansion Memory Boards for CPU 780 |
| | |
| Catalog Number | Memory Size |
| | |
| | |
| IC697MEM731 | 128KBytes |
| IC697MEM732 | 256KBytesw/256KBytesNon-VolatileFlashMemory |
|
| IC697MEM733 | 256KBytes |
| IC697MEM735 | 512KBytes |
|
Note that the current version of the expansion memory boards must be used with the CPU 780. consult your local PLC Distributor or PLC sales office for more information.
18 | Series 90-70 Hot Standby CPU Redundancy User's Guide ± December 1993 | GFK-0827 |
