ACB3 Dual Channel High Speed Sync/Async RS- 232 Serial Interface Features n Dual Channel Sync/ Async n 8530-8 SCC (Serial Communications Controller) n DMA Supports Data Rate Greater Than 1 Million bps Description n Full Duplex DMA Transfer Capability The ACB3 provides the PC with two direct synchronous/asynchronous links to RS-232 devices. RS-232 connections with full modem clocking n Selectable Port options are utilized, providing an industry standard interface to synchro- Address, IRQ Level nous data links, modems, and other devices. The Model ACB3 can be (2, 3, 4, 5) and DMA used in a variety of sophisticated communications such as SDLC, Channel (1 or 3) HDLC, X.25, and High Speed Assync. n RS-232 Interface Modem Control The Model ACB3 utilizes the Zilog 8530 Serial Communications Control- Signals Supported: ler (SCC). This chip features programmable baud rate, data format, TD, RD, RTS, CTS, interrupt control, and DMA control. DSR, DCD, DTR, TXC, RXC, TT n Software Program- mable Baud Rate n Software Developer’s Tool Kit Included with Source Code n DB-25P Interface Ordering Guide Cable Included with 2 Channel Boards ACB3 Board, manual Software n Higher Speed En- ACB3/SP Single channel board, manual, hanced SCCs and software CMOS SCCs Op- tional n Various Oscillators Available for Cus- tom Clock Rates Document 1030 05/04/99 Applications � Requiring Protocols Such As: SDLC, HDLC, X.25, MONOSYNC, BISYNC, and ASYNC � Fractional T1 Pipelines/Data Highways � PLC Communications � RS-232/422/485 Synchronous Communications Synchronous/Asynchronous Communications Serial Communication in most PC applications is asynchronous. Asyn- chronous communications is often not the best solution when higher data rates are required. Synchronous communication does not have the character synchronization over head of start or stop bits. Character synchronization can be achieved by many different methods when using synchronous communications. A common method for character synchro- nization is implemented by the transmission of "sync characters" or "sync flags". This is accomplished by transmitting a pre-defined bit pattern so that the receiver can lock on to the correct alignment of the data stream. Synchronous communication also differs from asynchronous communica- tion in the clocking of data bits. In asynchronous communications bit cell lengths are pre-defined on both the transmitting and the receiving ends. Both nodes must be programmed for the same data rate and communica- tion parameters (i.e. 9600, n, 8, 1). Synchronous communications defines each bit cell length on an additional clock signal that is provided by the transmitting node, receiving node or an independent clock source. This method allows the source of the clock to control the data rate on both the transmitter and receiver. Specifications SCC 8530-6 Number of Ports Dual RS-232 IRQ Requirements 8 I/O Addresses IRQ Selection 2-5 Maximum Data Rate Limited by RW-232 Specification Typically 64K bps DMA Channels 1 or 3 Maximum Data Distance Up to 100ft. Operating Temperature 0-50� C Storage Temperature -20-70� C Humidity Range 0-90% R.H. Current Specifications +5V @ 275 mA, +12V @ 50mA ea. Connector(s) DB-25P