B&R MAPPC800-ENG, User Manual

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Appendix A • Glossary
Panel PC 800 User's Manual V 1.00
RS232
R ecommended S tandard N umber 232 . Oldest and most widespread interface standard, also
called a V.24 interface. All signals are referenced to ground making this an unbalanced interface.
High level: -3 to -30 V, low level: +3 to +30 V; cable lengths up to 15 m, transfer rates up to 20
kbit/s; for point-to-point connections between 2 stations.
RS422
R ecommended S tandard N umber 422 . Interface standard, balanced operation, increased
immunity to disturbances. High level: 2 to -6 V, low level: +2 to +6 V; four-line connection
[inverted/non-inverted], permissible cable length up to 1200 m, transfer rates up to 10 MBit/s, 1
sender can transfer simplex with up to 10 receivers.
RS485
R ecommended S tandard N umber 485 . Interface standard upgraded from RS422. High level: 1.5
to -6 V, low level: +1.5 to +6 V; 2-wire connection [half duplex operation] or 4-wire connection
[full duplex operation. Cable lengths up to 1200 m, transfer rates up to 10 Mbit/s. Up to 32
participants can be connected to an RS485 bus [sender/receiver].
RTS
An abbreviation for " R equest T o S end". A signal used in serial data transfer for requesting send
permission. For example, it is sent from a computer to the modem connected to it. The RTS
signal is assigned to pin 4 according to the hardware specifications of the RS-232-C standard.
RXD
An abbreviation for "Receive ( RX ) D ata". A line for transferring serial data received from one
device to another, e.g. from a modem to a computer. For connections complying with the RS-
232-C standard, the RXD is connected to pin 3 of the plug.
SDRAM
An abbreviation for " S ynchronous D ynamic R andom A ccess M emory". A construction of
dynamic semiconductor components (DRAM) that can operate with higher clock rates than
conventional DRAM switching circuits. This is made possible using block access. For each
access, the DRAM determines the next memory addresses to be accessed.
SFC
Sequential function chart > Graphic input language for PLCs used to represent sequential
control.
Slot PLC
PC insert card that has full PLC functionality. On the PC, it is coupled via a DPR with the process
using a fieldbus connection. It is programmed externally or using the host PC.
S