MU-192
The MU-192 relay output module is designed especially to supervise traffic of Modbus RTU protocol via RS-485 (so-called "watchdog" functionality; abbreviation WD). Additionally, module can be used for standard "on/off" control of technological systems.
The module is equipped with two relays isolated from other circuits of module (power supply and RS-485 interface) with high insulation strength (safety isolation), signals within group of realy contacts are isolated with lower insulation strength. All relay outputs are protected against impulse overvoltage by 250VRMS varistors.
Both relay outputs can be individually interconnected to WD, or can work as standard digital outputs.
The module is equipped (in addition to two standard LEDs for power supply and RS-485 line activity) with two LED“s indicating the status of the relays.
Both WD circuits can be individually configured in-to one of two modes, "watchdog" and "retriggerable monostable flip-flop".
The "watchdog" mode uses two preconfigured timing constants ("initialization time" and "output activation time") and one timing parameters transmitted by the Modbus RTU protocol via RS-485.
After the supply voltage is turned on, the output remains in inactive state and the algorithm opens in the initialization phase. WD circuit remains in this phase until the first Modbus command, or the initialization time expires.
In case of time expiration, the output is set to the active state for the "output activation time" and then algorithm returns back to the initialization phase (i.e. broken Modbus RTU communication causes the output to be permanently switched between two states with preconfigured timing constants).
If the WD circuit receives a Modbus RTU command during initializing phase, the output remains in inactive state and the algorithm goes to the "count-down" phase (the algorithm can remain in this state for a maximum of the time defined as a parameter in the Modbus RTU command). In case of expiration, the output is set to the active state for the "output activation time" and then algorithm returns back to the initialization phase, but if the WD circuit receives a new Modbus RTU command during "count-down" phase, the algorithm remeains in reinicialized "count-down" phase.
The "retriggerable monostable flip-flop" mode works completely differently from "watchdog" mode.
After the supply voltage is turned on, the output remains in inactive state and the algorithm waits for the Modbus RTU command for an indefinite period of time (i.e. broken Modbus RTU communication causes the output stays permanently in inactive state).
If the WD circuit receives a Modbus RTU command, output is switched in-to active state and the algorithm goes to the "count-down" phase for a time defined as a parameter in the Modbus RTU command. In case of expiration, the output returns back in-to inactive state and algorithm waits for next Modbus RTU command, but if the WD circuit receives a new Modbus RTU command during "count-down" phase, the output stays in active state and algorithm waits for next Modbus RTU command.
Specifications
| Type | MU-192 |
|---|---|
| Numer of WD circuits | 2 |
| WD initialization time | 1÷999999s |
| "WD output activation time | 1÷999999s |
| Number of digital outputs | 2 |
| Type of digital outputs | C type relay |
| Relay parameters | 250VRMS/8A max. (30VDC/5A max.) |
| Output load | 3A continuously (5A max. 1s) |
| Isolation between contacts and power supply or RS-485 |
4kVRMS or 4kVDC (insulation gap & surface path 6.5mm) (see schematics) |
| Isolation between contacts | 1.5kVRMS or 1.5kVDC (insulation gap & surface path 2.0mm) (see schematics) |
| Supply voltage | 10÷30VDC |
| Power consumption | 1.8W max. |
| Housing & Dimensions | Modulbox 3M |
| Signal terminals | screw terminals, wire 2.5mm2 max. |
