Emerson PaCSystems VersaMax Series, User Manual, Page: 191 / 308

User Manual Chapter 11
GFK-1503F Jan 2020
The Service Request Function 177
Function # Description
9 Read Sweep Time from Beginning of Sweep
10 Read Folder Name
11 Read PLC ID
12 reserved
13 Shut Down the PLC
14 Clear Fault Tables
15 Read Last-Logged Fault Table Entry
16 Read Elapsed Time Clock
17 reserved
18 Read I/O Override Status
19-22 reserved
23 Read Master Checksum
26/30 Interrogate I/O
27, 28 reserved
29 Read Elapsed Power Down Time
31-255 reserved
11.2 Format of the SVCREQ Function
The SVCREQ function has three inputs and one output.
Figure 171
When the SVCREQ receives power flow, the PLC is requested to perform the function
number FNC indicated. Parameters for the function are located beginning at the reference
given for PARM. This is the beginning of the “parameter block" for the function. The number
of 16-bit references required depends on the SVCREQ function being used.
Parameter blocks may be used as both inputs for the function and the location where data
may be output after the function executes. Therefore, data returned by the function is
accessed at the same location specified for PARM.
The SVCREQ function passes power flow unless an incorrect function number, incorrect
parameters, or out-of-range references are specified. Specific SVCREQ functions have
additional causes for failure.