PMAC2A-PC/104
Base Board Hardware Setup
7
The ‘-‘ inputs of each differential pair each have a hard-wired 2.2 k
Ω
resistor to +5V; each also has
another 2.2 k
Ω
resistor as part of a socketed resistor pack that can be configured as a pull-up resistor to
+5V, or a pull-down resistor to GND.
If this socketed resistor is configured as a pull-down resistor (the default configuration), the combination
of pull-up and pull-down resistors on this line acts as a voltage divider, holding the line at +2.5V in the
absence of an external signal. This configuration is
required
for single-ended inputs using the ‘+’ lines
alone; it is desirable for unconnected inputs to prevent the pick-up of spurious noise; it is permissible for
differential line-driver inputs.
If this socketed resistor is configured as a pull-up resistor (by reversing the SIP pack in the socket), the
two parallel 2.2 k
Ω
resistors act as a single 1.1 k
Ω
pull-up resistor, holding the line at +5V in the absence
of an external signal. This configuration is
required
if complementary open-collector drivers are used; it
is permissible for differential line-driver inputs.
If Pin 1 of the resistor pack, marked by a dot on the pack, matches Pin 1 of the socket, labeled by a white
square, then the pack is configured as a bank of pull-down resistors. If the pack is reversed in the socket,
it is configured as a bank of pull-up resistors.
The following table lists the pull-up/pull-down resistor pack for each input device:
Device
Resistor
Pack
Pack Size
Encoder 1
RP30
6-pin
Encoder 2
RP31
6-pin
Encoder 3
RP36
6-pin
Encoder 4
RP37
6-pin
Summary of Contents for PMAC2A-PC/104
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Page 14: ...PMAC2A PC 104 Base Board Hardware Setup 8 ...
Page 34: ...PMAC2A PC 104 PMAC2A PC 104 Software Setup 28 ...
Page 41: ...PMAC2A PC 104 ACC 1P Hardware Reference Summary 35 ...
Page 51: ...PMAC2A PC 104 Base Board E Point Jumper Descriptions 45 ...
Page 55: ...PMAC2A PC 104 Acc 1P E Point Jumper Descriptions 49 ...