TETRA Data Modem with Voice Interface


Universal TETRA-Modem with Voice Interface


General Info

The TMO-100 is a data modem for TETRA infrastructures. With this device data can be transferred invisibly to one or more positions within a TETRA infrastructure. The TMO-100 is the all-in-one solution including controller, router, modem and mobile radio, which turns it into the ideal Turn-Key Solution.

Either serial as well as IP-based protocols can be communicated by this device. This is the reason, why the TMO-100 is equipped with two serial interfaces (optional RS-232 or RS-422/285) and also with one Ethernet port (10/100 MBits/s). For the data communication via a TETRA infrastructure the user can choose between SDS-based or Packet Data transfer.

The optional Voice feature offers the opportunity to connect a microphone speaker set and to contact a configured counterpart device. This is how co-workers are able to contact the control room on-site in case of emergency.

Furthermore, there is the opportunity to request the TMO-100 with internal inputs and outputs. The data of the inputs and outputs can be written on and be accessed through the Modbus-RTU protocol. Additionally, there is the possibility to send a status message in case of changes to another device ("unsolicited message" in case of alarm).

The TMO-100 is integrated into a robust anodized aluminum enclosure, which can easiliy be impemented to a DIN rail. The broad operating voltage range of 12-24 V (+/- 20%) makes it easy to integrate the device in automation facilities.


Serial Communication Protocols

Different applications, and different geographical regions, have different requirements for automation protocols. Energy utilities in Germany and Europe use common standards (IEC 60870-5-101 or IEC 60870-5-104). In Asia and the U.S. they generally use the Modbus RTU or DNP3 protocol. Less well known is the PakBus Sinaut protocol from Siemens, which is primarily used in the water and sanitation industries.

The Modbus RTU Protocol is particularly good for slow or wireless transmission paths, due to its user-friendly and solid structure. However, compared to other protocols, the Modbus RTU Protocol has the disadvantage that the outstation exclusively works by polling, which is the cyclical polling of each individual station by the master station. Other protocols have the advantage of the outstations using event-driven messages, rather than waiting to be polled by the master. Through this process, alarms can be reported independently from the polling cycle of the Master device.

The TETRA TMO-100 supports protocols such as Modbus, PakBus, the Sinaut protocol from Siemens and many more. The TM-100 does not generally (but can if required) work with GISSI, but each single data set will be sent to the one outstation it is addressed to. This is a major benefit of TETRA infrastructures, due to the high network load when sending group messages, rather than selective messages. Another feature that reduces the network load is the integrated modified LZ77 data compression mechanism.

For the Modbus RTU Protocol the TMO-100 offers a special option to make it possible to process event-driven alarms on a spontaneous basis. For this the outstations can be ordered with an optional E/A Board in addition to their serial interfaces. These inputs can be used to automatically send status alarm messages to the master station. This master station stores the alarms in Modbus registers, where they can be accessed at any time though the connected master-PLC or the SCADA Server. This makes it possible to react to alarms or malfunction messages at any time, in the same way as unsolicited messages.


IP-Data Transmission

In addition to the serial asynchronous protocols, the TMO-100 can also process UDP- and TCP-protocols. In this case, the device operates as a TETRA router. After the device is turned on, a PPP-connection is automatically established to the TETRA infrastructure, and the unit receives an IP-Network address from the TETRA Switch. The TMO-100 immediately send IP data from the local Ethernet interface to the TETRA-IP-world, and vice versa. For this the TMO-100 uses NAT, Port Forwarding and Port Translation, which turns the device into a fully-featured TETRA-router. For the user connected on the local IP-Port, the TETRA infrastructure is not actually visible. He simply connects the PLC to the Ethernet port and, after setting up the IP-Address, will be able to communicate with other devices or the SCADA Server within the TETRA infrastructure (and also, if enabled, beyond that). The device can be configured either via the embedded Web server, the Modbus RTU Protocol using its serial interface, or the Modbus/TCP via its local Ethernet interface, or remotely via the TETRA infrastructure.


Voice and Data Connection

Another important characteristic for data modems is the ability to set up a voice connection. Using an eight-pole RJ45 plug, an RSM (remote speaker microphone handset) can be attached to the TMO-100. When the PTT (push to talk) button on the RSM is pressed, the modem disconnects all data connections (SDS, CSD, PSD) and automatically switches into voice mode. A voice call is set up to either a preset ISSI or GSSI. After finishing the conversation, the data communication will automatically be restarted by the device. When switching from voice mode to data mode or vice versa, the modem can still send a status message to the control center.


Data Compression

To optimize the amount of data in TETRA Infrastructures the TMO-100 is equipped with a data compression and decompression mechanism. Depending on the structure of the data sent, the TMO-100 can compress the data to 25% up to 80%.


SCADA = Supervise Control And Data Acquisition

SCADA is an automation device, to remote surveil, remote control and remote data polling for process data. On-site these data are gathered by RTUs (Remote Terminal Unit) or PLCs (programmable logic controller) and are send through wireless or wire-bounded data transmission to the control room. This room is typically equipped with monitoring equippment, to visualize the polled measured data and alarms.The data polling can either occur in polling operation (cyclical polling of the outstations one after the other) or event driven (alarm message).

This is why the Modbus RTU protocols only works with polling operation; other protocols like the IEC 60870-5-101 or the DNP3 are able to work in polling operation and to send event driven alarms without polling simultaneously.

The TMO-100 supports all serial protocols mentioned above, as well as all IP-based protocols, either as serial TETRA data modem or TETRA IP router. For the Modbus RTU protocol to TMO-100 offers a special feature, to make it even for Modbus possible to send out event driven alarms. For this reason, the outstations can additionally be equipped with an I/O board. The inputs of this I/O board send status alarm messages to the master radio station, which signals change in any way. The master radio station stores the alarms into Modbus registers, where they can be easily polled from the master PLC.



TMO-100 Unique TETRAModem with Voice

Type of Device: TETRA Modem for Serial Communication
TETRA Device for SDS and Status Messages
RF-Output Power: Pout up to 3 Watt (400 MHz)
Pout up to 1 Watt (800 MHz)
Frequency Range: According to TETRA Standard

Serial Interfaces:





RS-232 or RS-485/422, Subin-D 
RS-232 or RS-485, RJ12

Ethernet-Interface 10/100 MBit

Voice: Voice with Microphone Speaker Set (RJ45)
Operating Mode: SDS-based Data Transfer
Status Message via Alarm Inputs
Packet Data based Communication
Circuit Switched Data
Protocols: Modbus-RTU, Modbus/TCP
IEC-60870-5-101, IEC-60870-5-104
Customer Specific Protocols
Field Strength Display:
LED-Bargraph on the device
Operating Voltage: 12-24 Volt DC +/- 20%
Average Current Consumption:



<50mA @ 24V
<80mA @ 12V

Enclosure: Anodized aluminum with plastic ends; according to DIN 43880
Operating Temperature: -20°C to +65°C
Mounting: 35mm DIN Rail

80mm x 162mm x 62mm

(excluding antenna and socket)