ABB TPU2000, Technical Manual, Page: 42 / 374

TPU2000/2000R Modbus/Modbus Plus/ Modbus TCP/IP Automation Guide
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IRIG B time synchronization is available for the products listed in Tables 4-6 and 4-7. Generally, three types of
protective relays do not offer IRIG B, units without a communication card, units with Modbus Plus communication
cards, and units with DNP 3.0 communication cards.
Each of these units uses the AUX COM port located at the rear of the relay to accept the TTL IRIG B signal. The
DPU/TPU/GPU2000R and DPU1500R use Pins 63 and 64 to accept the IRIG B negative polarity and IRIG B
positive polarity signals respectively, as illustrated in Figure 4-11. The DPU/TPU2000(R) and DPU1500R use
pins 65 and 66 as illustrated in Figure 4-12.
Com 3
55 56 57 58 59 60 61 62 63 64
RS485 Isolated Port
IRIG B Positive
IRIG B Negative
Figure 4-11. DPU/TPU/GPU2000R and DPU1500R IRIG B Connector Placement
C
O
M
P
O
R
T
AU
X
PO
R
T
74 73 72 71 70 69 68 67 66 65
RS485 Isolated Port
IRIG B Positive
IRIG B Negative
Figure 4-12. DPU/TPU2000 IRIG B Connector Placement
ABB’s implementation of IRIG B requires that the signal be daisy-chained to each device. Each device in the
IRIG B network presents a load to the IRIG B receiver/converter. Daisy-chained inputs are simple parallel
circuits. A sample calculation is shown for the example illustrated in Figure 4-13.
If the input impedance of each DPU/TPU/GPU2000/R is measured at its IRIG B connection, the impedance would
be 1000 ohms. Each IRIG B input requires less than one mA to drive it.