Operator Manual
Page
36
of
40
P/N 1580281
SEC3120 Digital Transmitter
Sensor Electronics Corporation
Rev 10, 20150707
Careful network planning is necessary before deployment concerning Sensor Roles, Modbus Network ID
mode, Relay Mode, etc. Paramount would be the consideration of the use of an SEC3500 HMI Panel as
the Modbus Master;
If used in the initial deployment, then the Sensor Role for each SEC3120 must be decided and the
correct Modbus Network ID mode defined so that if sequential network IDs are needed to support
a dual sensor SEC3120, the assignment of network IDs is planned in advance. Take special care
when mixing SEC3100 Digital Transmitters with SEC3120 Dual Digital Transmitters on the same
Modbus Network to avoid overlap or potential future overlap as upgrades in the future may occur.
Plan for future additions and upgrades- the Modbus Network may add more SEC3120 Digital
Transmitters, replacement of SEC3100 Single Digital Transmitters with SEC3120 Dual Digital
Transmitters, and SEC3120 Digital Transmitters that may initially start out as Single Sensor Role
configurations may be upgrade to dual sensor roles through the addition of additional sensors to
the Transmitters.
Make sure that there are enough gaps in the Network ID value planning to accommodate the initial
deployment as well as future upgrades.
If a complete overhaul of the Modbus Network ID layout is planned, it is probably easier to just
delete all devices at the SEC3500 HMI Panel and then reconfigure all devices first before
rediscovering the changes at the SEC3500 HMI Panel.
Caution: Do not mix an SEC3500 HMI with ANY other Modbus Master of any type!
Bus contention,
poor performance and corruption can result. If other Modbus gateways are needed in addition to an
SEC3500 HMI, then utilizing the SEC3500 HMI Panel’s Ethernet Modbus Slave Interface as a gateway
interface as a better solution for capturing the sensor data to another network bus or higher level software
management function.
