PMSTR-4000
Quick Start Tips
September 15, 2021
Page 3
USING MODBUS MONITOR TO VERIFY COMMUNICATION STATUS
A Modbus monitoring program such as ModScan or Shortbus Modbus Scanner can be
used to check if communication is active. Connect the Ethernet port of the PMSTR-4000
to a PC and set up a static IP address to match that of the PMSTR-4000. By default, the
IP address of the PMSTR-4000 is 192.168.0.11, but this can be immediately changed
from option groups 13 through 15. Set up the PC address to have a different last octet
from the PMSTR-4000 – an example would be to set the PC static IP address to
192.168.0.19.
Use the Modbus monitoring program to read registers 00020 through 00027. These
indicate the following:
00020 – status of unit 1 (0 = no communication, 1 = communication active)
00021 – status of unit 2 (0 = no communication, 1 = communication active)
00022 – status of unit 3 (0 = no communication, 1 = communication active)
00023 – status of unit 4 (0 = no communication, 1 = communication active)
00024 – status of unit 5 (0 = no communication, 1 = communication active)
00025 – status of unit 6 (0 = no communication, 1 = communication active)
00026 – status of unit 7 (0 = no communication, 1 = communication active)
00027 – status of unit 8 (0 = no communication, 1 = communication active)
SENSOR ISSUES
If the process control sensor (steam or hot water) does not have a valid reading, the
PMSTR-4000 will override the virtual HAND-OFF-AUTO position of each unit and force
each into HAND. The PMSTR-4000 does this since it is not possible to control the load
without a sensor connected. Placing each unit back into HAND allows them to control to
their local sensor and maintain an output. Since the units will all be in HAND, it will not
be possible for the units to be ONLINE when there is a sensor issue.
