Troubleshooting, Specification – Obvius A8923-4 User Manual
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Supported Modbus commands:
0x03 Read Holding Registors
0x06 Preset Single Register
0x11 Report Slave ID
All other Modbus commands return "Illegal Function" . The Status Register is the only register that is read/write.
Device ID = 50
Device name = "Obvius 4A4P-M2"
* Status Register (40013)
* Pulse State Register (40017)
Bits 0-3 Analog input type. bit 0 is Analog 1
0=4-20mA, 1=0-10V (read/write)
Bits 4-7 Analog overcurrent/voltage. bit 4 is Analog 1
0=Ok, 1=Alarm (read-only)
Bits 8-11 Analog broken 4-20mA wire. bit 8 is Analog 1
0=Ok, 1=Alarm (read-only)
Bit 12
Debounce feature slows down the pulse scan rate for mechanical relays
0=250Hz Max, 1=20Hz Max (read/write)
Bit 13
1 = resets min/max/average to current value (read/write)
Bit 14
bit is unused. Always 0
Bit 15
1 = set learn mode (read/write)
Bit 0
Pulse 1 status
0 = contacts open, 1 = contacts closed
Bit 1
Pulse 2 status
0 = contacts open, 1 = contacts closed
Bit 2
Pulse 3 status
0 = contacts open, 1 = contacts closed
Bit 3
Pulse 4 status
0 = contacts open, 1 = contacts closed
bits 4-15 Unused
The Obvius A8923-4 ships from the Factory configured for 0-10V. Press the Learn button if 4-20mA products are used.
When changing a single bit in the status register: First read the register from the IO module, next, set or clear the bit as needed and then write
the register value back to the IO module. Simply writing 0x20 to set the pulse input debounce feature will also force all analog inputs into 4-
20mA mode.
Troubleshooting
Power LED is not on:
Ensure 24VDC is present and polarity is correct.
Data LEDs do not blink:
Check network wiring, address selection. Verify master Modbus controller is functioning.
Pulse LEDs do not blink: Verify pulse inputs are dry contact or opto-isolator wired with correct polarity.
Analog values inaccurate: Verify analog devices are wired correctly. Press LEARN button to re-configure.
Verify Modbus master is configured to scale sensor outputs properly.
Check sensor output range. Make sure Modbus master is configured with correct scaling.
No output from unit:
Check network wiring, address selection. Verify Modbus master device is configured to read correct points.
Specification
Inputs
Power
24vdc, 50mA, + converter powered analog devices
Analog
4-20mA or 0-10v auto-detected (ranges and units set in master device)
0-10v Input impedance = 10k ohms
4-20mA Input Impedance = 250 ohms
Scan Rate 250mS (1/4 second)
Pulse
Dry contact, 250Hz max. (user selectable to 20Hz max)
input impedance 500 ohms max.
Accuracy
+/- 0.25% F.S. (Analog Input)
Output
Hardware
RS-485, 2-wire , non-isolated
Protocol
Modbus RTU Protocol, 9600baud
Latency
5mS
Configuration
Address
6-position DIP switch, 63 addresses
Analog Input
Auto-detecting 0-10v or 4-20mA (ranges and units set in master device)
General
Dimensions
4-module, 70mm x 86mm x 58mm(h)
Material
Base part: Black Noryl UL94-V0; PCB material: FR-4
Mounting
Compatible with M36 DIN-RAIL (EN50022)
Operating Environment 0 to 50 degrees C, 0 to 95%RH non-condensing
3300 NW 211
th
Terrace, Hillsboro, OR 97124, Ph: +1-503-601-2099
Date: Jun 21, 2010
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