General Information; Specifics - PEP Modular Computers CP345 Manual

CP345
2. Functional Description

2.1 General Information

The CP345 serial communications controller board is the realization of a low cost, high
speed solution for industrial automation communication purposes and represents the
implementation of a serial communication controller board at the basic OSI levels.
The main functions implemented on the CP345 board are the OSI Layer 2 control for
RS232, RS422 and RS485 communication purposes as well as the OSI Layer 1
physical signal level adaptation for the above mentioned interfaces, where the RS422/
RS485 interface is realized for half duplex as well as for full duplex operation.
Enhanced communication features such as optoisolated serial interfaces or frontend con-
nector options are realized by means of a dedicated transition module, the CP345-TR1,
interfaced to the CP345 mainboard directly via the common serial interface, or via a rear I/
O module. In fact, a non-optoisolated variant of the CP345 can be equipped with rear-I/O
connectivity. If a rear-I/O module is used, the frontend signals are routed to a J2 rear-I/O
connector.
The physical layer adaptation (OSI Layer 1) of the CSI-TTL interface signals is realized
independently for each channel via corresponding on-board RS232, RS422/RS485
transceivers where each of the four serial communication links are configured individu-
ally for serial interface operation per software including the serial line termination for bal-
anced serial communication.
The supply voltage for the CP345 is 5V DC. The transition module for the optoisolated
board variant is provided with two 5V/5V on-board DC/DC converters, one for the chan-
nels 0/1 and one for 2/3.

2.2 Specifics

The OSI Layer 2 functions for serial communication are handled entirely by the Siemens
enhanced, DMA supported, intelligent serial communication controller DSCC4. This
controller handles all the onboard serial communication tasks related to OSI Layer 2
comminication tasks for synchronous and asynchronous serial communication, signifi-
cantly reducing the workload to the system host CPU.
Configuration of the serial communication links for the various operation types as well
as serial line termination for differential communication (RS422/RS485) is accomplished
via software. The four serial I/O channels are independent and can be software config-
ured individually for RS232, RS422/RS485 serial communication.
Data transfer operation of the serial channels is indicated at the front panel by four,
channel-related pairs of LED's for the indication of receive and transmit operations.
All the above mentioned communication functions including the RS232, RS422 and
RS485 serial I/O functions are tied to the host system via the standard CompactPCI
interface provided directly on the Siemens serial communication controller DSCC4.
Work load data transfer to and from the PCI host system is done in a DMA based man-
ner for all four serial channels. Logical control of the CP345 serial communication oper-
ID 19979, Rev. 03 © PEP Modular Computers GmbH
Functional Description
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