HP 27130A Technical Reference Manual page 40

SID SID
NO. MNEMONIC
o
RTSA-
(OUTPUT)
Table 3-6. SIO Special Functions
MUX CARD
MNEMONIC FUNCTION
EN_SED- Active LOW. When asserted, the
RS-232-C/RS-423-A single-ended
drivers are enabled. Otherwise,
the transmission lines (SDs) of
the single-ended drivers are
held in a MARK condition (negative
vol tage).
To assert the EN_SED signal, a 1 must
be written into bit 1 of SID 0 channel
A, register 5.
On power up (reset), EN_SED is
unasserted, i.e., the transmission
lines (SDs) of the single-ended
drivers are in a MARK condition.
o
DTRB- EN_DD Active HIGH. When asserted, the
RS-422-A differential drivers are
enabled. OtherWise, the
transmission lines (SD(A), SD(B»
of the differential drivers are
held in a high impedance state.
(OUTPUT)
To assert the EN_DD signal. a 0
must be written into bit 7 of SID 0
channel B, register 5.
On power up (reset), EN_DD is
asserted. i.e., the differential
drivers are enabled.
3-13
HP 27130A