Answering frequently asked Questions (Firmware V.107)

Transcription

1 FAQ EasyConn Profibus plug Answering frequently asked Questions (Firmware V.107) EasyConn LEDs: While connected, the Profibus connector offers the following test functions for start-up and trouble shooting indicated by LEDs as below: Name Color LED off LED on LED blinking (5Hz) PWR green No Power Self-test finished, Power OK Short-circuit of bus wire possible. Blinks simultaneously with ERR LED. TXD green No bus activity - Data transfer active Term green No termination Termination active Internal terminating resistor faulty. Blinks simultaneously with ERR LED. ERR yellow No errors detected Signal levels out of defined range, possibly termination failure in bus line. Short-circuit of bus wire possible respectively internal resistor faulty. The LED flashes sporadically: The Profibus device is near the reference level, which is defined in the Profibus connector. Appearing differences were compensated by the protocol. Answering frequently asked Questions: Q1: Which signals are measured at which pin? What kinds of values are measured: levels, impedances? A: EasyConn measures A-line (pin8) and B-line (pin3) signals levels and analyses its absolute levels and amplitudes in specified time points depend on CNTR (pin4) signal and Termination switch On/Off state. Other words, EasyConn processes also amplitudes trend. EasyConn measures and processes only levels, not impedance. A Profibus telegram not detects and analyses! Q2: How do we measure? A: The signals on lines as well as on the terminator resistor divider network compare with number of fixed voltage references. Then controller calculates amplitude for A and B lines. The data transfer detects by buildin comparators. All EasyConn controller pins are inputs; EasyConn not manipulates lines and not disturbs signals! Q3: Which signal levels are rated "ok" (ERR LED off)? What are the top and bottom limit programmed? A: There aren t "top" and "bottom" limits for signal levels. The "No (faulty) termination(s) in the bus lines" (ERR LED ON) error is a result of amplitudes trend data processing. For more details of processing algorithm see the Appendix. VIPA GmbH Firmware V

2 EasyConn Profibus plug FAQ Q4: Are there possible interpretations for different combinations of LED signals? A: ERR LED Flashing The ERR LED Flashing with 5 Hz: - Profibus driver failed (defective RS485 driver) with PWR LED additionally flashing. - Short-circuit of wires (A-B lines or line and shield short circuit in EasyConn; cable s wires swapped in some of EasyConn; defective RS485 driver) with PWR LED additionally flashing. - Internal terminating resistor(s) faulty (defect, poor solder) with Term LED additionally flashing. In Termination switch ON state Short-circuit of wires make also Internal terminating resistor(s) faulty (termination resistor has short circuit) so ERR, Term and PWR LED s will flash simultaneously. ERR LED ON "No (faulty) termination(s) in the bus lines" state. The ERR LED ON "No (faulty) termination(s) in the bus lines" indicates faulty bus termination in PROFIBUS itself (for example, terminating resistors deactivated on one or both bus end connectors). Attention! In this case bus state is not stable and depends on cable s length, bus parameters, data baud rate etc. Therefore, not all connectors in the bus may detect and indicate this error permanently. Q5: How does EasyConn determine that the device is transmitting? Why TxD LED is ON during net activity? A: EasyConn detects device transmitting by monitoring net activity during positive logic pulse CNTR signal. If Profibus device not provides CNTR signal (or CNTR line not connect to connectors Pin 4) but net activity is present - "TxD" LED constantly ON. Q6: Why does EasyConn currently repeat self-test instead of going on line? A: The EasyConn maximum power consumption (all LED s on) is 25mA. The operation voltage range for EasyConn controller is V. Accordingly with Profibus recommendations maximum of 90mA at the 5V (±5%) output (pin6) of Profibus device connector should be provided. If a device provide, for example, only 10mA, the power voltage on EasyConn will drops below 2.2V during self-test (all LED s on), EasyConn controller resets and self-test starts again. 2 Firmware V. 107 VIPA GmbH

3 FAQ EasyConn Profibus plug Appendix "No (faulty) termination(s) in the bus lines" error. Processes Algorithms Main Algorithm The Algorithm consists of two steps, "Step 1" and "Step 2". Each Steps itself uses a "Single Measuring" procedure with different parameters. Single Measuring Line (A/B) amplitude measuring synchronizes with positive edge of CNTR signal. Measuring time is by default ~280µs. Single error fixes when minimal level for any pulse is less or equal 0V and maximal level for any pulse is greater then +3.6V during measuring time ("red box", see Examples). Step 1. Digital Filter 280 Temporary "No termination" error presets only for continuous sequence of 32 single errors for both lines. Step 2. Digital Filter 20 This Algorithm starts only when Temporary "No termination" error was preset in Step 1. Additional line amplitude measuring synchronized with falling edge of CNTR signal. Measuring time for this measuring reduced from 280µs to 20µs. Single error fixes when minimal level for any pulse is less or equal 0V and maximal level for any pulse is greater then +3.6V during measuring time ("blue box", see Example 4). "No termination" error confirms only for continuous sequence of 32 single errors for both lines. Result Thereby a true "No termination" error (ERR led ON) sets only when both algorithms returns errors. The Examples below illustrate possible bus conditions for different RS485 transceivers witch can be used in Profibus devices. Conditions: Cannel 2 (CH2) Line A signal (pin 8) Cannel 3 (CH3) CNTR signal (pin 4) Red box measuring window for "Step 1" Blue box measuring window for "Step 2" VIPA GmbH Firmware V

4 EasyConn Profibus plug FAQ Example 1: High-speed RS485 transceivers (for example DS75176). Bus Termination is ON. No error. 4 Firmware V. 107 VIPA GmbH

5 FAQ EasyConn Profibus plug Example 2: "No Termination" in bus line. "No termination" error. 1V/div 2V/div VIPA GmbH Firmware V

6 EasyConn Profibus plug FAQ Example 3: 40Mbps, Profibus RS-485 transceivers (for example MAX3469). Bus Termination is ON. Fast drivers switches picks may produce sporadic single errors. False Alarm works around with "Digital Filter 280". Example 4: Profibus Digital Isolator (for example NVE IL3585 and ADM2486) Bus Termination is ON. Faster lines discharge time may produce temporary "No termination" error on "Step 1". False Alarm works around with "Digital Filter 20". 6 Firmware V. 107 VIPA GmbH