OSSD Output and Safety Circuit
The MB3 has an OSSD (Output Signal Switching Device) output for the user to form a
simple safety circuit in their system. When the system is error free, the MB3 energizes
the OSSD output and it will de-energize the OSSD output if an error has occurred.
Most drives will give an OK signal or “Servo Ready” or similar, by energizing its
appropriate output and connected external devices will receive this status. The MB3
collects all OK signals from various devices through terminal inputs X203 - X210 and
then sends out an OK signal to the next device.
However, if there is an error feeding in, MB3 will send out a “Not OK” signal by de-
energizing the OSSD output and the external safety circuit will cut power and stop the
hazard.
Using a magnetic contactor as an external device is a simple way to disconnect the
power supply from the drives or the VFD. The “OVR“(Override) input is provided for
temporarily energizing the magnetic contactor, which lets the machine operator
recover from the error.
To activate this function, the user needs to select one or more inputs from X203 to
X210. Then by creating a solder bridge across the appropriate corresponding solder
pads, i203 to i210, which are shown in Figure 27 on page 24, the chosen inputs will
become part of the safety circuit.
Figure 24 shows the safety circuit block and relevant I/O including, inputs, solder-
bridge, and override input and outputs.
Warning. The MB3 utilises only a simple safety circuit. There is no guarantee it will
protect against a serious external failure. It is therefore advised that the user MUST
ALWAYS check the functionality of any external circuit that is connected to the MB3.
Safety
Circuit
i
203
i
204
i205
i
206
i
207
i208
i
209
i
210
Safety OVR (override)i202
OSSD
Figure 24, On board safety circuit
www.CNCRoom.com Page 22
To Next Page
Loading...
Need help?
General