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Other Considerations
Application Flexibility
The units support tail circuit and null modem functions for DCE to DCE or DTE to DTE communications. This
requires two of the same TD unit.
An alternate interface (V.35 or RS‐232) may be installed at the opposite end, allowing the user to create a link
between two electrically incompatible interfaces without requiring a separate interface converter. For more
information, please see the "Optical Compatibility" table.
SFP MSA Compliance
The SFP Multi Source Agreement (MSA) is an agreement that was drafted among competing manufacturers of
SFP optical modules. The SFF Committee was formed to oversee the creation and maintenance of these
agreements including the SFP MSA designated as INF‐8074i. This agreement describes a mutually agreed upon
standard for the form and function of SFP modules. However, not all SFPs produced are MSA compliant. The
MSA provides for a transceiver (TX/RX) pinout. Other industries such as broadcast had the need for dual TX
and dual RX SFP for uni‐directional applications such as video. Naturally, a non‐MSA standard was introduced
allocating pinout assignments for dual output and dual input I/O configurations. In addition, the some of the
internal serial communication pins were reassigned.
The TD‐1580/TD‐1581 will only accept MSA compliant SFP modules which support the specified data rate.
PIN
Transceiver (MSA)
1
VEE
2
TX_FAULT [VEE]
3
TX_DIS
4
MOD_DEF(2) ‐ SDA
5
MOD_DEF(1) ‐ SCL
6
MOD_DEF(0) – PRESENCE [VEE]
7
Rate [NC]
8
LOS
9
VEE
10
VEE
11
VEE
12
RD‐
13
RD+
14
VEE
15
VCC
16
VCC
17
VEE
18
TD+
19
TD‐
20
VEE
Pinout Comparison Chart
Transceiver (Non‐MSA)
VEE
VEE
NC
VEE
SCL
SDA
VEE
RX1_LOS
NC
NC
VEE
Rx1‐
Rx1+
VEE
VCC
VCC
VEE
Tx1+
Tx1‐
Tx1_DIS
Dual TX (Non‐MSA)
VEE
NC
NC
VEE
SCL
SDA
VEE
Tx2+
Tx2‐
Tx2_DIS
VEE
NC
NC
VEE
VCC
VCC
VEE
Tx1+
Tx1‐
Tx1_DIS
Dual RX (Non‐MSA)
VEE
Rx2‐
Rx2+
VEE
SCL
SDA
VEE
NC
NC
NC
VEE
Rx1‐
Rx1+
VEE
VCC
VCC
VEE
NC
NC
NC
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