Watlow PPC-2000 - Manual (Page 306)

Appendix A: Modbus Protocol PPC-2000 User’s Guide
278 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Diagnostics Subfunction -- Return Diagnostic Register 02
The contents of the slave’s 16-bit diagnostic register are
returned in the response.
Subfunction Data Field (Query) Data Field
(Response)
00 02 00 00 Diag. Register
Contents
Diagnostics Subfunction -- Force Listen Only Mode 04
Forces the addressed slave to its Listen Only Mode for Modbus
communications. This isolates it from the other devices on the
network, allowing them to continue communicating without
interruption from the addressed slave. No response is returned.
When the slave enters its Listen Only Mode, all active
communication controls are turned off. The ready watchdog
timer is allowed to expire, locking the controls off. While in this
mode, any Modbus messages addressed to the salve or
broadcast are monitored, but no actions will be taken and no
responses will be sent.
The only function that will be processed after the mode is
entered will be the Restart Communications Option function
(function code 8, subfunction 1).
Subfunction Data Field (Query) Data Field
(Response)
00 04 00 00 No Response
Returned
Diagnostics Subfunction -- Clear Counters 10 (0A Hex)
Clears all Communication Event counters. Counters are also
cleared upon power-up.
Subfunction Data Field (Query) Data Field
(Response)
00 0A 00 00 Echo Query Data
Diagnostics Subfunction -- Return Bus Message Count
11 (0B Hex)
The response data field returns the quantity of messages that
the slave has detected on the communications system since its
last restart, clear counters operations, or power-up.
Subfunction Data Field (Query) Data Field
(Response)
00 0B 00 00 Total Message Count