Dwyer SCD - Manual (Page 6)

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7 LED DISPLAY
1. If the power supply is normal, POWER LED will be on.
2. LED will be on after the power is switched on. 1 second after the power is on, the communication protocol will
be displayed and the next second the communication address will be displayed. After that, LED will all be on to
show that the operation is normal.
3. When the control is executing, RUN LED will be on.
4. When errors occur during the input, memory, or communication, ERROR LED will be on.
5. When output is enabled, the corresponding LED will be on.
6. When PID program is in auto-tuning parameter, AT LED will flash.
7. RX LED will flash when receiving communication signals and TX LED will flash when transmitting
communication signals.
Protocol format of LED display when the power is on
AT TX RX O1 O2 Err Run
000: 2400bps 001: 4800bps
010: 9600bps
011: 19200bps 100: 38400bps Parity 00: None 01: Even
10: Odd 0: ASCII
1: RTU 0:2 Stop bit
1:1 Stop bit
Communication address display: AT (bit 6) and Run (bit 0) will combine into binary code.
8 PASSWORD PROTECTION
The default of password will not function. After you write the 4-byte password into a specific communication
address, the password function will be enabled. There are three levels of password protection.
1. Level 1: only LED status, settings, and input values can be read via communication. Changes cannot be made.
2. Level 2: only LED status, settings, and input value can be read via communication. Settings can be changed.
3. Level 3: all the settings can be read via communication. Settings and AT adjustment can be changed.
4. No password function.
Once the password is set (106EH~1070H), the controller will enter level 1. To enter other levels, enter the
corresponding passwords in 106BH ~ 106DH (see Address and content of Data Register). After the power is
switched off, it will return to level one. If you wish to disable the password protection, clear all password settings.
To enable the password protection, write in corresponding passwords (106EH ~ 1070H) when the password
status is disabled. To disable password levels, specific function address 106EH ~ 1070H shall be written into the
intended password settings.
The password status can be read from 106EH ~ 1070H. Statuses of each bit are shown in the table below.
Bit b0 b1 b2 b3 b4 b5 b6
Status Level 1 Level 2 Level 3 Level 1
locked
Level 2
locked
Level 3
locked
Unlock
Bit = 0 refers to no password setting. Bit = 1 refers to password is set (b0~b2). b3~b6 are used for displaying current password status.
9 SYNCHRONOUS COMMUNICATION PROTOCOL & AUTO NUMBER ID FUNCTION
By using Auto Number ID function, the communication protocol of SCD2000 can be set the same as the one in
SCD1000. ID numbers tend to increase.
1. Set the auto communication flag to be “1” for SCD1000 (communication address 1022H).
2. Switch off the controller before connecting it to another SCD2000. After that, switch on the power again.
3. Communication default: 9600bps, 7 bits, Even, 1 stop bit.
4. The function will result in additional 3 ~ 5 seconds needed for the power to be switched on.
10 RS-485 COMMUNICATION
1. Transmission speed supported: 2,400, 4,800, 9,600, 19,200, 38,400bps.
2. Formats: 7, N, 1 or 8, E, 2 or 8, O, 2.
3. Communication protocol: Modbus (ASCII or RTU)
4. Function code: 03H to read the content of register (max. 8 words). 06H to write one word into register. 01H to
read bits data (max. 16 bits). 05H to write one bit to register.
5. Address and Content of Data Register: