Possible Reasons for Bad comms to stations

Site Installation

1. Faulty Wiring, loose connections, wires not inserted into terminal blocks properly - check with long nose pliers. Not following wiring diagrams.

2. Incorrect comms cable used, all the same low capacitance data loop cable should be used for ALL connections, all data loop sections should be of same cable.

3. Cable section between station joins wrong cable type (some stations ok on one end of join, others are retrying many times).

4. Noise interference from other electrical gear (check rx.txt after Diagnostic Run to see rx data from stations).

5. Recent site wiring changes, change in location of computer.

6. Noise signal interference into A16 (makes lines go up and down badly or all stay at about -7 Deg C on -50/+50 range)

7. Extending RS232 cable. Should not use RS232 at any distance greater that 15 m. Dont cut and extend supplied gray RS232 cable with moulded plugs.

8. Power interference into A16 from VSDs. Noise from electrical cables getting into 2100-MR, especially from VSDs or long cable runs (causes unexplained offsets in value).

9. Terminating Resistors too low in value or not mounted at end of data loop. Dont use 120 ohm terminator with 2100-IS.
NOTE: Terminating resistors MUST be used with 2300-XX stations, 2300-NET, USB-485 to 2300-XX stations.

Station Equipment

1. Stations Faulty (check heartbeat, RX and TX, TXE LEDs) - damaged by power spikes.

2. W01 Comms bridge on IN2000-IS or IN2000-AI faulty (measures 3.5v to 4.5v dc across pins 8 & 16 of 3486 422 chip).

3. RS422 or RS485 linking not correct on 2100-A16 (links should be in parallel with terminals according to updated drawings in A16 manuals)

4. Water damage to stations.

5. 2100-A16 power supply overloaded (TXE LED will flash approx 1 per second with no comms activity).

Converter

1. Plug pack from 2100-IS not plugged in, cables removed from back of 2100-IS (check LEDs to see if flashing), cable disconnected from back of computer to 2100-IS. Measure plug pack on converter is above 9V DC (terminals 74,75). 

2. IN2000-IS, 2100-IS Faulty - easiest thing to replace if old converter on site than replacing stations, Note terminal numbers are different from IN2000-IS to 2100-IS - follow numbers written in manual not RX+, RX- etc text. 2100-IS has better noise rejection and TVS's on its 422 inputs.

3. Incorrect DIP switch settings in converter.

Computer

1. COM port on computer faulty (driver.exe locks up dead - try USB port).

2. USB driver not working properly. Try different brand of USB converter, new drivers.

3. Moving location of computer - extend RS422 line and move converter to new computer location, do not extend RS232 from new computer location to existing IS converter box location.

4. RS232 lead removed from back of computer.

5. USB to Serial Converter must not be used if the computer is mounted in a control panel environment. Electrical noise can stop the USB converter from working properly.

2100-NET - networking

Check Windows system log for TCP/IP messages indicating lost network connections.

1. Check Hub - try replacement hub.

2. Network TCP-IP connection issues for 2100-NET, 2100-A16-NET (use ping, check LEDs on XPORT are alive, use laptop and local switch to check station OK) Check Inactivity timeout has been set to XPORT can reset itself if network goes down.

3. If attempting to connect new gear with 2100-NET such as a PLC, do test connection with 2100-IS and COM port with laptop to determine correct terminal wiring.

4. Comms settings for 2100-NET to PLC are set in the XPORT (baud, parity, etc) using XPORT Installer or Web Interface - not set in MicroScan.

Possible Checking Steps to eliminate source of problem.

Try different converter. Check DIP switches in converter correct.
Double check wiring - use terminal numbers as written in 2100-IS/2100-A16 manuals
Check no terminating resistor installed or installed at end of data loop. Dont use 120ohm resistors, use 1K.
Use Find Stations to detect stations, check LEDs on converter and A16 comms terminals, (TXE and TX flash for sending data, RX flash for receiving data).
Check A16 beat LED is flashing. Check TXE Led is not flashing by itself with no comms.
Turn off one by one equipment of the data loop & use Find Stations
Remove equipment from dataloop & use Find Stations to find remaining equipment.
Any site wiring changes recently ?
Any sign of water damage in cabinets ?
2100-XX comms linked correctly for 422 or 485 - check manual for correct orientation of links.
Check Station Status (double click on COMS at bottom of navigation tree) to see indications of good vs bad stations.
Check diag.txt and rx.txt for station error messages.
Check 2100-IS plug pack power supply is putting out correct voltage (should be above 9v DC).

Actual Site Fault List

Bad Comms to A16, SR90.
Faulty 9v Plug Pack putting out incorrect voltage (4V).

Bad Comms to A16, FP23, SR90.
Terminating Resistor too low value, not on end of data loop, in middle.

Bad comms to 485 A16
A16 comms links set incorrectly.
H2 Comms links L1, L2 position for 422, L3,L4 position for 485.

No comms to A16
TXE LED on A16 flashing. Terminal 49 shorted to ground.

Good comms to some stations, Bad to some others on a data loop.
Part of a data loop was wired with correct comms cable, the bad stations were on a section with incorrect comms cable.

Intermittent bad comms to IN2000-XX stations.
Faulty older IN2000-IS converter. Did not fail in workshop tests though. 

Bad Network Comms
Faulty Hub. Replace Hub.

Bad Readings from 2100-A16
Customer had extended RS232 cable, now going 50m, instead of max of 15m.

Bad Readings from 2100-A16
Noise induction from switching gear in same cabinet as 2100-A16

Intermittent Bad Readings from 2100-MR
Noise induction from VSD into cable between MR and 2100-A16.

Bad comms to a new station added
Wire join in comms cable, short between strands in wire between terminal 73 and 74 (COM).

Bad comms to 422 2100-D
Station linked for 485 operation. Change links to 422.
H2 Comms links L1, L2 position for 422, L3,L4 position for 485.

Bad comms to A16 and old IN2000-IS converter.
Check to make sure correct RS232 cable is used, as some signal lines in RS232 lead are used to power the converter.

Bad coms to Shimaden Controllers
Check comms wiring, Shimaden Protocol Settings are correct, and 485 delay is long enough (COM  LED on controller only lights up when controller has been sent COM write command from the computer).

Blown A16 power supply.
Connect 240v to an A16 linked to 'M' power supply setting.
Power supply diode D2 must be replaced.

Bad comms to 3x2100-A16
Fault traced to using USB to serial converter in control panel.
Replace converter with PCMCIA serial card in laptop or PCI to serial card.

Bad Comms to SLC50X PLC
Faulty Power supply in PLC.

Bad Comms to Omron C Series PLC
Poor connection in RS232 cable. Pin 5 (GND) on DB9 not connected on computer end.