TPU2000/2000R Modbus/Modbus Plus/ Modbus TCP/IP Automation Guide
64
Utility devices require that no event is to be missed in the field IED. ABB has incorporated one method in which a
device is notified that events have occurred in the field IED between host polls. The method employed for 1x data
(Modbus Function Code 02) data collection of rapidly changing momentary signals is Momentary Change Detect.
MOMENTARY CHANGE DETECT is independent of the protocol. These ABB innovations allow Modbus protocol
to address and satisfy the concerns common to a utility installation. The two functionality’s are those in excess of
the real time status access that Modbus function code 02 affords.
Momentary Change Detect
status is incorporated using two bits to indicate present status and momentary
indication status. The odd bit is the status bit and the even bit is the momentary bit. The status bit indicates the
present state of the element accessed. The momentary bit indicates element transitioning more than once
between IED reads. The momentary bit is set to a “1” if the element has transitioned more than once. The bit is
reset upon a host access. Addresses 10513 through 11056 are allocated for momentary change bit detect status
detection. NOTE: MOMENTARY BITS MUST BE READ IN PAIRS.
An example of momentary change detect is illustrated in Figure 5-20. Suppose a host device monitors
TPU2000R physical input bit 1. Figure 5-20 illustrates the physical input transitions of input 1. At each field
voltage rising edge/falling edge transition, the status of the Modbus contact 1x addresses are listed. The dotted
line arrows indicate the poll received by the TPU2000R and the state of both the status bit and the momentary
indication bit. Note that the even bit (momentary change detect) resets itself to a zero state after a host read.
EC
INPUT 1 (ADDR 10272)
REAL TIME STATE
10272 INPUT 1
echo’s that of 11049 when read.
1
0
MOMENTARY STATE
11055 STATUS
INPUT 1
11056 MOMENTARY
INPUT 1
TIME = 0
0 1 1 0 0 1 0 0 1 0 1 1
0 0 0 0 0 0 1 0 0 1 1 0
HOST READS
TPU 2000R
11055 = 1
11056 = 0
HOST READS
TPU 2000R
11055 = 0
11056 = 0
HOST READS HOST READS
TPU 2000R TPU 2000R
11055 = 0 11055 = 1
11056 = 1 11056 = 1
11056 RESETS AFTER HOST
READ. INPUT 1
STATE TRANSITIONED
MORE THAN ONCE
BETWEEN HOST ACCESSES
Figure 5-20. Momentary Change Detect Example
Logical Inputs (34 Elements Defined 2 Winding TPU2000/2000R - 80 Elements Defined 3
Winding TPU2000/2000R)
This section of relay information allows access of relay element data. Some of the status bit information reported
in 1X discrete response is available as 0X-register definition table. All of the individual information is available in
the 4X-register definition table (Modbus Function Code 03). Table 5-5 lists the discrete point address assignment
for physical inputs and control elements within the TPU2000/2000R.
Table 5-5. Logical Input Modbus Address Map Definition
Note Register
Address
Item Description
10001:
87T
2 or 3 Winding 3- Phase % Differential Current Control
10002:
87H
2 or 3 Winding 3 Phase % High Set Instantaneous Differential
Current Control
Summary of Contents for TPU2000
Page 10: ......
