Date Code 20010719 701 Motor Protection Relay
Modbus
®
RTU Communications Protocol
User-Defined Modbus Data Region
C.17
User-Defined Modbus Data Region
The SEL-701 Relay Modbus Register Map defines an area of 125 contiguous
addresses whose contents are defined by 125 user settable addresses. This feature
allows you to take 125 discrete values from anywhere in the Modbus Register Map and
place them in contiguous registers that you can then read in a single command. The
SEL-701PC software provides a convenient method to define the User Map Addresses,
download the configuration to a particular relay, and store the configuration for use
with other relays.
To apply the user-defined data region, follow the steps listed below:
Step 1. Define the list of desired quantities (up to 125). Arrange the
quantities in any order that is convenient for you to use.
Step 2. Refer to Table C.18 on page C.19, and list the address of each
quantity.
Step 3. Set the SEL-701 Relay User Map Addresses (00D0h–014Ch) equal
to the addresses of the desired quantities using the SEL-701PC
software and a PC connected to the front-panel serial port.
Step 4. Use Modbus Function Code 03h or 04h to read the desired quantities
from addresses 0050h through 00CCh (User Map Values) at the rear-
panel EIA-485 port.
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