RS485 encoder

RS485 encoder is a general term for encoders with RS485 free protocol on output interface. The RS485 protocol is a standard that defines the electrical characteristics of drivers and receivers in a balanced digital multipoint system. The standard is defined by the Telecommunications Industry Association and the Electronics Industry Alliance. Digital communication networks using this standard can effectively transmit numbers under long-distance conditions and in environments with high electronic noise. RS485 makes it possible to connect to the local network and the configuration of multi-branch communication links. The electrical interface with RS485 protocol can be connected to PLC to realize intelligent control.

There are various types of RS485 encoders, such as absolute and incremental, photoelectric and magnetoelectric, high-precision and common types. At present, there are various types of RS385 encoders in the brands of Kaidi.

Key features of RS485 encoder:

Differential transmission increases noise immunity and reduces noise radiation

Long-distance links, up to 4000 feet (about 1219 meters)

Data rate up to 10Mbps (about 12.2 meters within 40 inches)

Multiple drivers and receivers can be connected to the same bus. The wide common mode range allows ground potential difference between the driver and receiver, and the maximum common mode voltage is -7-12V.

RS485 encoder setting method:

1. Read parameters: (valid when programming allows the line to be connected to high level)

Host computer sends: D+00+A+0D Encoder response: X+address+a+direction+baud rate+working status+working mode+0D

(Encoder address 01, clockwise increase, baud rate 19200, reciprocating mode, passive mode.)

2. Set address: (valid when programming allows the line to be connected to high level)

Host computer sends: D+address+B+new address+0D encoder response: X+address+b+new address+0D

(Change address 00 to 01)

3. Setting direction: (valid when programming allows the line to be connected to high level)

Host computer sends: D+address+C+new direction+0D encoder return: X+address+c+new direction+0D

(Change clockwise to counterclockwise)

4. Set the baud rate: (valid when programming allows the line to be connected to high level)

Host computer sends: D+address+E+new baud rate+0D encoder response: X+address+e+new baud rate+0D

(Change the baud rate to 19200)

5. Set the resolution of each circle: (valid when the programming allows the line to be connected to high level)

The upper computer sends: D+address+F+resolution+0D encoder response: X+address+f+resolution+0D

(Set the resolution to 3600)

6. Set active and passive mode: (valid when programming allows the line to be connected to high level)

The host computer sends: D+address+I+mode+0D encoder response: X+address+i+mode+0D (Set to Q&A mode)

RS485 communication protocol description:

Baud rate: 4800bps. 9600bps. 19200bps. 38400bps. 115200bps.

Frame format: 8 data bits, 1 stop bit, no parity, no control flow.

The parameters of the encoder require software instructions to set the encoder.

When the encoder is in active mode, the encoder actively sends data to the upper computer. The data length is 16-bit hexadecimal ASCII code, the format is:

XAB>±DATA↙, namely:

12345678910111213141516

X address>±DATA↙

Among them, "X" is the leading letter,> bit separator, and ± is the sign bit. DATA is data, ASCII format, 10 bits, composed of 0-9, range

It is -9,999,999,999～+9,999,999,999. The last is the carriage return (0D).

When the encoder address is in passive mode, it is the question and answer mode. The host computer sends an inquiry instruction to the encoder, the instruction is a 4-digit hexadecimal ASCII code, and the format is:

D+AB↙.

Programming allows the use of wire (blue)

When setting the mode, the blue wire and brown wire of the encoder are connected to the positive power supply together, and the white wire is connected to the power ground wire. At this time, the communication rate of the encoder is fixed at

19200bps.

In non-setting mode, that is, when working normally, it is recommended to connect the blue and white wires together to the power ground wire.

Note for RS485 communication:

1. Communication speed and transmission distance are a pair of contradictions. The higher the rate, the closer the transmission distance, but the more stable, and vice versa.

2. When the external electromagnetic interference is strong, the external setting line needs to be connected to the high level when setting the encoder, but it is recommended to be forced to connect to the low level after the setting is completed to prevent encoding

The amplifier suddenly returns to zero due to external interference.

3. When the external electromagnetic interference is strong, it is best to use double-shielded cables for RS485 wiring.

4. When multiple encoders are connected to the upper computer, since the data returned by the encoder does not have a parity check, it is recommended to return each encoder in time when the upper computer is programmed.

The data returned are distinguished.

5. When there is a motor in the system, the encoder power supply must be isolated from other power supplies.

Since the RS485 circuit is in a differential form, A+ and B- are all voltage-carrying, grounding or connecting to a high level for a long time will cause damage to the RS485 circuit

1. Characteristic parameters

Working voltage 10-30Vdc or 5Vdc polarity protection

Current consumption <110mA (24V power supply) <190mA (12V power supply)

Output signal ModbusRTU, can set length and angle application output

Output load capacity ≤ 400 ohm, standard work 200-250 ohm

Resolution 4096

Number of laps 4096

Working temperature -25—70℃ Temperature range during programming: 0℃～＋70℃

Storage temperature -40—100℃

Protection grade IP65

Allowable speed 2400 rpm

Output refresh cycle <1.4ms

Connection cable 1 meter 8-core shielded cable, or 9-core socket

Shape features: Clamping synchronization integrated flange, metal shell, sealed double bearing structure (see the figure for the dimensions)

Rotary shaft clamping synchronous integrated flange shaft diameter 10mm or 6mm, length 20mm, including D-plane, stainless steel material