Appendix A: RS-485 Communication Interface

1 General Information

The communication interface is employed to connect the TR-101 device to RS-485 network. The device utilization within RS-485 network allows for the following functions:

• collecting data of measured temperatures within SCADA system;
• setting device parameters with use of configuration software;
• remote control of the channels output relays.

RS-485 as an interface standard has found extensive industrial application; it provides for establishing networks with node count of up to 247 and data transfer at distance of up to 1200 m. With use of duplicators, the number of nodes and the transmission distance can be increased.

All network devices are connected in a serial bus (Figure A1). To maintain the reliable operation of transmitters/receivers and to eliminate interference impact, the communication line ends must be equipped with a terminating resistor of impedance Rсогл = 120 Ohm that is connected immediately to the device terminals (see Figure A1).

Figure A1 – RS-485 Network Connection Diagram

Note

The device is connected to a PC via RS-485 / RS-232 or RS-485 / USB interface adapter.

The data exchange may take place at one of the following bitrates: 2400, 4800, 9600 bps.

2 Remote Control for Power Relays

By installation the value rSA = 2 (Table 7.1) device will be switched to the mode of remote management power relay. Control registers are shown in Table A2.

If the channel working with two level action and labeled to control register value 0 or 1 is possible to switch on or switch off prorated power relay.

If the channel working with PID regulation and labeled to control register value 0 or 100 is possible to manage capacity plug into correspondent relay (pos. 3.2.6.6 of manual).

If the mode “Remote management of power relay” is switched on TR-101 continuous working in usual mode.

Exception is the fact that management of power relay is passed to operator.

3 Data Exchange Adjustment Through Interface RS-485

Data exchange adjustment is realized by parameters:

Parameter	Mnemonic	Description
Switching	rSA	Set switching on (switching off) RS-485 and the mode of remote management
Identifier	rSn	Device base address (1…247)
Bit rate	rSS	Rate of exchange data online (2400, 4800, 9600 bit/s)
Timing	rSL	Time delay of the packet answer 0-99.9 ms

Device TR-101 has following fixed exchange parameters not shown at the indicator:

• Quantity Stop-bit: 2
• Length of a data word: 8
• Parity check: not

Caution

New option exchange values come into effect only after device restarting or restarting at RS-485.

4 Data Exchange Through Interface RS-485

4.1 Connection Setup

Working through interface RS-485 it should be done relevant connection (p. 1 of Appendix A) and set the value of net parameters (p. 3 of Appendix A).

4.2 Network Master

For organization data exchange online through interface RS-485 necessary have net Master. The main function of this device is to activate data exchange between sender and recipient. TR-101 may work at Slave mode by ModBus RTU protocol.

4.3 ModBus Protocol

ModBus is the open network protocol that was developed by company Modicon. Protocol description available at website www.modbus.org.

Register addresses of program parameters are shown in Table 7.1 of the manual.

Check list of supported functions (Modbus) is shown in Table A1.

Additional registers and their functions are shown in Table A2.

Supported Modbus Functions

Table A1 – Supported Modbus Functions

Function (hex)	Sub-function	Description	Note
0x03	—	Receiving value of one or several registers	max. 125
0x06	—	Recording one value to the register	—
0x08	0x00	Return query data	Diagnostics
0x08	0x01	Communication options restart	Diagnostics
0x08	0x04	Setting up “listen only” mode	Diagnostics

Additional Registers

Table A2 – Additional Modbus Registers

Device Identification

Address (dec)	Name	Description	Note
0	Device ID (MSB)	TR-101 – 0x0002	ID
1	Device ID (LSB)	Firmware version - v53	Version

Status Register (Address 2)

Bit	Description
bit 0	0 – no emergency; 1 – Emergency (emergency code in register)
bit 1	0 – relay of channel 1 is switched off; 1 – relay of channel 1 is switched on
bit 2	0 – relay of channel 2 is switched off; 1 – relay of channel 2 is switched on
bit 3	0 – relay of channel 3 is switched off; 1 – relay of channel 3 is switched on
bit 4	0 – relay of channel 4 is switched off; 1 – relay of channel 4 is switched on
bit 5 – bit 15	reserved

Emergency Register (Address 3)

Bit	Description	Display
bit 0	0 – Not emergency; 1 – EEPROM rejection	EEP
bit 1	0 – Not emergency; 1 – parameter mistake	ErP
bit 2	0 – Not emergency; 1 – sensor 1 short circuit	FCC
bit 3	0 – Not emergency; 1 – sensor 2 short circuit	FCC
bit 4	0 – Not emergency; 1 – sensor 3 short circuit	FCC
bit 5	0 – Not emergency; 1 – sensor 4 short circuit	FCC
bit 6	0 – Not emergency; 1 – sensor 1 disconnection	FOC
bit 7	0 – Not emergency; 1 – sensor 2 disconnection	FOC
bit 8	0 – Not emergency; 1 – sensor 3 disconnection	FOC
bit 9	0 – Not emergency; 1 – sensor 4 disconnection	FOC
bit 10 – bit 15	reserved

Temperature Registers

Address (dec)	Name
4	Sensor temperature 1
5	Sensor temperature 2
6	Sensor temperature 3
7	Sensor temperature 4

Relay Control Registers

Address (dec)	Name	When ch = 1 (Two-position)	When ch = 2 (PID)
8	Register of relay control 1	0 – relay OFF; 1 – relay ON	0 – capacity 0%; 100 – capacity 100%
9	Register of relay control 2	0 – relay OFF; 1 – relay ON	0 – capacity 0%; 100 – capacity 100%
10	Register of relay control 3	0 – relay OFF; 1 – relay ON	0 – capacity 0%; 100 – capacity 100%
11	Register of relay control 4	0 – relay OFF; 1 – relay ON	0 – capacity 0%; 100 – capacity 100%

Reserved Registers

Address (dec)	Description
12-20	Registers from 12 to 20 are reserved (equal to zero always)