The SOM1 Serial Output Module is designed to be used with IBM PCs and compatibles. Each module has 4 independent single pole changeover relays which can be independently addressed from the PC. The standard RS232 serial output is converted to RS485 by the first module and this is used to drive subsequent modules. Each module may be allocated one of 256 addresses, thus allowing for control of 1024 relays. Addresses are selected using an 8 way DIL switch and more than one module can have the same address.
This will allow several relays to be controlled simultaneously. Modules can be physically placed in positions remote from the PC. The link from the PC Serial Port to the first module is restricted to approximately 50 metres. After that modules can be located as much as 200 metres apart. Connection between the PC and the first module would normally use a standard null terminated modem lead connected to the 9 pin 'D' connector.