Signal Specifications
Each serial signal (control, status, data, or clock) is compatible with an electrical specification that is
selected by placement of jumpers on the card. This section briefly describes the specifications supported
by the card.
Single Ended Signals (RS-232/V.28)
SyncLink single ended signals are compatible with RS-232 and ITU V.28 standards. Each signal has one
connector pin. Single ended signals share a common ground conductor.
The following voltages are measured with respect to ground.
•
Maximum Voltage Range: +15 to -15V (between signal and ground)
•
+3V to +15V (+5V typical) = control/status signal on or data value of 0
•
-3V to -15V (-5V typical) = control/status signal off or data value of 1
•
Voltage between -3V to +3V = invalid (indeterminate) state
•
Max cable length 50 feet
•
Max data rate 20kbps
The maximum data rate of 20kbps is part of the RS-232/V.28 standards. The SyncLink card can operate
at speeds up to 120kbps depending on the cable length and loading. Longer cables and increased
loading reduces the maximum supported data rate.
Differential Signals (RS-422/RS-485/V.11)
SyncLink differential signals are compatible with RS-422, RS-485 and ITU V.11 standards. Each signal has
two connector pins, named A and B. These pins are also named -/+, but this convention can be inverted
depending on context and manufacturer. Use A and B to avoid confusion.
A common ground conductor is recommended, but not required, to reduce common mode voltages
between cable ends which may result in incorrect or impaired operation.
The following voltages are measured pin A with respect to pin B of each signal. Probing pin A with
respect to ground (single probe) gives a positive voltage or ground, corresponding to the positive and
negative differential values. Probing pin B with respect to ground gives a positive voltage or ground,
with inverted polarity from pin A.
•
Maximum Voltage Range: +6 to -6V (between conductors in a pair)
•
+200mV to +6V (+2V typical) = control/status signal on or data value of 0
•
-200mV to -6V (-2V typical) = control/status signal off or data value of 1
•
Voltage between -200mV to +200mV invalid (indeterminate) state
•
Max cable length 4000 feet
•
Max data rate 10Mbps
Longer cables and increased loading reduces the maximum supported data rate.
