RS485 isolated repeater – PML/1
PML/1 is an RS485 isolated repeater, powered at low voltage.
It can be used to regenerate an RS485 signal and, at the same time, isolate up to 400 V two sections of a system that communicates over an RS485 bus.
It accepts a wide range of low-voltage AC and DC power supplies, is fully Plug & Play, and requires no drivers or DIP switches. Both the non-isolated RS485 port and the RS485 port isolated up to 400 V operate in half-duplex mode. The RS485 isolated repeater automatically detects data direction and baud rates up to 250 kbps, so it can be easily installed in any new or existing system.
It can be mounted on a control panel with a 35 mm DIN rail and it’s very compact, only 1 DIN module.
Description
PML/1 is an RS485 isolated repeater, powered at low voltage. It can be used to isolate up to 400 V two sections of a particularly noisy serial communication, or to regenerate a signal in long-distance transmissions. It can be mounted on a control panel with a 35 mm DIN rail and it’s very compact, only 1 DIN module.
It accepts a wide range of low-voltage AC and DC power supplies, is fully Plug & Play, and requires no drivers or DIP switches. Both the non-isolated RS485 port and the RS485 port isolated up to 400 V operate in half-duplex mode. PML/1 RS485 isolated repeater automatically detects data direction and baud rates up to 250 kbps, so it can be easily installed in any new or existing system.
Use cases
Serial repeaters are used to regenerate the signal on an RS485 bus and, at the same time, isolate a very noisy device or segment. Electromagnetic interference is common in industrial environments, so it is good practice to isolate the various sections of an RS485 bus. Isolation protects devices from possible power surges or electromagnetic interference, but it also ensures signal integrity.
In case of heavy electromagnetic interference (EMI), it is recommended to use an optical fiber segment, which ensures perfect electrical isolation.Optical fiber also provides complete protection from adverse events such as power surges and lightning strikes, which are otherwise impossible to contain on a copper-only bus.
Even a short synthetic optical fiber segment, paired with two converters such as CMM/1S, completely isolates a branch of a system from lightning, provided that the different sections of the system and the converters are powered by different transformers or power supplies.Synthetic optical fiber is particularly suitable for this kind of isolation, as it is very easy to lay and needs no termination.CMM/1S converters are also particularly suitable because they have screw-type connectors for synthetic optical fiber, so no specialized tools are needed and installation is very simple.
Protocol
PML/1 RS485 isolated repeater is completely independent of the protocol used. This means that the repeater is transparent to the communication and can be used with protocols such as Modbus, BACnet, or any proprietary protocol.
This is possible because the repeater operates on electrical levels rather than at the protocol level itself. Therefore, this RS485 isolated repeater can also be used in complex networks where multiple protocols are present simultaneously on the same RS485 bus.
Versatility
The RS485 isolated repeater is also available with a 230 V power supply, or in optical fiber versions. PMLP/1 industrial serial repeater is functionally identical to PML/1 but operates on 230 V mains voltage. Alternatively, the optical repeaters with RS485 output TSS/1M and TVV/1M are available, with synthetic and glass fiber respectively.
TSS/1R and TVV/1F use other serial standards, RS232 and RS422, with various optical fiber combinations. Other combinations of serial standards, optical fiber, and power supply are available in the catalog, while special requests (such as higher baud rates) can be made via the contact form.
Technical Specifications
Caratteristiche principali
| Alimentazione | 9 – 24 V AC 48/62 Hz 9 – 30 V DC |
|---|---|
| Assorbimento | 1 W |
| Velocità di trasmissione | 0 – 250 kbps (automatica) |
| Ritardo di propagazione | 600 ns (tipico) |
| Tensione di isolamento | 400 V (DIN EN 60747) – 2500 V per 1 minuto (UL 1577) |
RS485
| Communication type | Half Duplex on a balanced line, with automatic data direction |
|---|---|
| Maximum bus voltage | ± 60 V – ESD ± 16.5 kV (Human Body Model) |
| Common mode range | ± 25 V DC |
| Slew rate | Limited, to have an error-free transmission |
Mechanical features
| DIN Rail | 1 module |
|---|---|
| Dimensions | 90 mm x 18 mm x 57 mm |
| Weight | 52 g |
Working conditions
| Degree of protection | IP20 |
|---|---|
| Operating temperature | -20 °C to +50 °C |
| Storage temperature | -40 °C to +80 °C |
