Which initial state do the MR-DO(A)4 outputs have after a reset or communication loss?
Is defined by the value in register 1 (see software manual).
The Modbus module with 4 digital outputs was developed for decentralized switching tasks. It is suitable for switching electrical components, such as motors, contactors, lamps, louvers, etc. In this case it is necessary to protect the relay contacts by appropriate load-dependent measures. The outputs can be switched by means of standard registers via a Modbus master. Module address, bit rate and parity are set with 2 rotary switches on the front or by software. Suitable for decentralized mounting on DIN TH35 rail according to IEC 60715 in electrical distribution cabinets.
Which initial state do the MR-DO(A)4 outputs have after a reset or communication loss?
Is defined by the value in register 1 (see software manual).
What can I do if the red ERROR LED on the module lights up or there is no communication?
There are several possible causes, please check the following:
- Operating voltage (A1 / A2) connected and sufficient for the device.
- BUS (A- / B+) connected and not reversed. Pay attention to (- / +), not to A/B.
- Address (rotary switches) set correctly, must not occur twice or be 0.
- Bit rate and parity (rotary switches) set correctly, only possible in programming mode (see mounting note).
- Shielded and twisted pair cable used.
- Termination resistor (120 Ω) set on both sides.
- Bias resistors available on the BUS.
- Timeout high enough for all participants to respond (approx. 10 ms).
What can I do if the red ERROR LED on the module lights up or there is no communication?
There are several possible causes, please check the following:
- Operating voltage (A1 / A2) connected and sufficient for the device.
- BUS (A- / B+) connected and not reversed. Pay attention to (- / +), not to A/B.
- Address (rotary switches) set correctly, must not occur twice or be 0.
- Bit rate (rotary switches) set correctly, only possible in programming mode (see mounting note).
- Shielded and twisted pair cable used.
- Termination resistor (120 Ω) set on both sides.
- Bias resistors available on the BUS.
- Max Master as high as the number of physical master I/Os on the BUS.
- Max Frame high enough for all answers from participants to get through (BMT-RTR setting).