The PD22 logger is destined for telemetering computer systems as an intermediate element in the data exchange between the object side and the master system. 
The logger speeds up the data exchange between devices and the master system. Moreover, it allows to increase the number of devices connected to the system.
Two serial ports are used for communication. The first port (Port 1) having two RS-485 interface systems, destined to communicate with devices working in the object. The second port (Port 2) has RS-485, RS-232C and USB interfaces, destined to communicate with the master system through wire links.
An asynchronous MODBUS character communication protocol has been implemented on the serial link. The logger has a real time clock.
Parameter set of the logger serial link
 Address  1... 247
 Baud rate  1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200bit/s,
 Working mode   ASCII, RTU
 Information unit          

 ASCII: 8N1, 7E1, 7O1; 7N2

 RTU: 8N2, 8E1, 8O1, 8N1

The data logger realizes following functions
Readout of process parameters values from devices which are accessible as logger parameters,
Archiving of process data with a defined frequency, which are made available on demand for the master system (390000 records),
Archiving of emergency events (44400 events),
Data exchange consisting in transmission of demands from the master system to the specific device, eg. readout or parameter record,