Interface Characteristics - Emerson Motorola MVME162 User Manual

Serial Interconnections
A
Table A-4. Serial Port B EIA-530 Interconnect Signals (Continued)
Pin
Number
23
24
25

Interface Characteristics

In specifying parameters for serial binary data interchange between DTE and
DCE devices, the EIA-530 standard assumes the use of balanced lines, except
for the Remote Loopback, Local Loopback, and Test Mode lines, which are
single-ended. Balanced-line data interchange is generally employed in
preference to unbalanced-line data interchange where any of the following
conditions prevail:
The interconnection cable is too long for effective unbalanced operation.
The interconnection cable is exposed to extraneous noise sources that may
cause an unwanted voltage in excess of ±1V measured differentially
between the signal conductor and circuit ground at the load end of the
cable, with a 50Ω resistor substituted for the transmitter.
It is necessary to minimize interference with other signals.
Inversion of signals may be required (e.g., plus polarity MARK to minus
polarity MARK may be achieved by inverting the cable pair).
EIA-530 interface transmitter and receiver parameters applicable to the
MVME162 are listed in Tables A-5 and A-6.
A-6
Signal
Mnemonic
DTR_B Data Terminal Ready (B). Output from DTE to DCE indicating that the
DTE is ready to send or receive data.
TxCO_A Transmit Signal Element Timing—DTE (A). Control signal that clocks
output data.
TM_A Test Mode (A). Indicates whether the local DCE is under test. In DTE
configuration, ignored. In DCE configuration, always tied inactive and
driven false.
Signal Name and Description
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