Seneca S6001-RTU, User Manual

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USER MANUAL – Z-TWS4/Z-PASS2-S/S6001-RTU
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In this chapter, all the FBs and functions available on Z-TWS4/Z-PASS2-S/S6001-RTU are listed, providing a
description of input/output parameters and some notes for each of them.
19.1 Function Blocks
19.1.1 General FB behavior
The description given in this paragraph apply to all the FBs available on Z-TWS4/Z-PASS2-S/S6001-RTU,
except for the LINUX_SHELL FB, which has a particular behavior (see related paragraph).
All the FBs require more than one PLC cycle to be completed (Asynchronous Function Block); so, the
application shall run them for a number of cycles until it detects that the FB execution has ended.
Every FB has an “ENABLE” parameter, which is an input/output parameter: to let the FB actually run, the
application shall put ENABLE=TRUE (input), not changing the parameter value during the FB execution;
when the execution is completed, the FB code itself will put ENABLE=FALSE (output); when the FB is called
with ENABLE=FALSE, it does nothing and returns the NOT_DONE (-2) result value.
All the FBs return the FAILED (-1) result value to signal that the FB execution has failed, for a generic
reason; some FBs provide further failure result values, in particular the TIMEOUT (2) result value.
All the FBs return the RUNNING (0) result value to tell the application that the FB processing is still running
and the DONE (1) result value when the FB processing has successfully ended.
19.1.2 FTP_GET
The FTP_GET FB downloads a file, by means of the FTP protocol.
When first called, the FB runs a process which starts performing the download;
on subsequent calls, it only checks if the process has finished its job.
The FB has the following input parameters:
- HOST : IP address or host name of the FTP server
- PORT : TCP port for the FTP protocol (normally: 21)
- USERNAME : username for authentication