Seneca Z-PASS1, Руководство пользователя

Страница: 82 / 155

USER MANUAL – Z-PASS1/Z-PASS2
82
The Mode=BRIDGE option is particularly useful for Modbus RTU devices with the “Fail Safe” feature
available for output lines, as for many Seneca devices; normally, those devices are designed to put their
output lines to “fail safe” value, when the connection to the master (e.g. a SCADA system) goes down; since
the criterion to detect the “connection failure” is that no Modbus (write and read) request is received, the
“fail safe” mode can’t be entered with “classic” gateway behaviour.
Finally, tags with Mode=SHARED MEMORY are stored only in CPU memory, not in any RTU device, so their
values are written/read only when a Modbus write/read request is received for those tags on the Modbus
TCP/IP side.
NOTE: all considerations related to requests received on the Modbus TCP/IP side identically apply to
requests received on a serial port configured as Modbus RTU Slave.
By clicking on the “APPLY” button, the tag is added/modified and the following page is shown.