User manual

Doc-ID: EAPCEN Page 11
Date: 16.12.2015
7.5 Commands
The app window can reveal an extra part by clicking on the “Show command” button. This allows the user to directly
access the device with commands in either ModBus or SCPI (where featured) protocol/language format, in order to
query other information from the device or to access functions which are not available in the upper window part.
Figure 7 - Direct commands
The tabs “SCPI” and “ModBus” both offer a selected set of commands to choose from and send by click on the “Send”
button. Further SCPI commands can be directly typed into the input box (see external documentation “Programming
ModBus & SCPI”, which is also delivered with the device on CD or USB stick), while further ModBus commands can be
created in tab “Free work” by selecting registers and function codes according to ModBus RTU standard.
All commands sent and answers received in the selected mode are logged with time stamp in the window part on the
right-hand side. The example screenshot above shows that SCPI command *IDN? has been sent to a PSI 5000 device
and the device responded after approx. 20 ms.
While SCPI is a text based command language it is logged in the ASCII tab, ModBus is a binary format and thus logged
in the Hex tab.
7.5.1 Limitations
 The log does not record all commands in parallel in ASCII and Hex tabs
 When switching between tab “SCPI” and tab “ModBus”, the input mode for the command input box also
changes, meaning that typing a SCPI command while ModBus mode is selected won’t result in correct trans-
fer and execution and vice versa, if SCPI mode is active