Unico SSI Serial Encoders

Overview

The Unico 319-663 encoder appears to be the same as the Hengstler Type RA 58 SSI 24 bit serial encoder. There are 12 bits for counting revolutions and 12 bits for the rotational angle. These bits are put together in one 24 bit gray code data word. There is an alarm bit that follows the 24 bit count. According to the Hengstler catalog, the alarm bit responds to low voltage, high temperature, broken disk or faulty LED.

Information on this encoder is available from the Hengstler catalog “Shaft Encoders, Linear and Angular Measuring Systems 2001”. Danaher Controls (Ph. 800-234-8731) can supply the catalog.

The encoder power supply is specified between 10V and 30V, so it should be powered from an external supply rather than the TI-5000JX. Connect an external bench supply to the +V and 0V pins of the encoder. Be sure to also connect the 0V line to J1 pin 2 of the TI-5000JX to ensure a common ground system. While the power supply is greater than 5V, the serial signals are 5V levels. 

Types Supported

The following list shows the Hengstler serial encoders that are currently supported by the TI-5000JX:

 

Identification

These encoders are clearly marked with the part numbers shown in the previous section, so identification should be no problem. The Hengstler part number is Type RA 58. The Unico part number is 319-663.

Connection

A cable for this encoder is not currently offered. The connector is a 12 pin connector of the type used on the Indramat encoders, except the pin rotation is reversed. Cabling for the Hengster/Unico encoders is the TI-5636 as shown below:

 

The TI-5000JX really only uses the 0V reference and the data and clock true and complement lines. If the Direction* line is left disconnected, the count increases for CW rotation. To reverse the direction connect the Direction* line to the 0V Signal line.

Testing

Hengstler/Unico serial encoder types listed above (like most serial encoders) use only the Data Display and the Serial Count Test. No information on the Unico motor (such as forward armature direction) is available at this time.

 

Data Display

Data Display is the initial test, and it is started by default when Athena is started. When already in another test, it can be started by clicking on the Data Display button among the test buttons at the top of the display. Use it for the following:

1. Turn the encoder to ensure that the encoder is counting approximately the right number of counts per revolution.

2. Use the commutation display to check or set the feedback commutation alignment.

3. Check the encoder status for the following: ensure that the encoder is indexed, communicating properly with the tester, not reporting internal errors, correctly displaying overheat and battery alarms, and displaying the correct encoder ID (if ID is implemented).

The following sections describe information shown on the display.

Commutation

The electrical angle can be used to check and set commutation using a static rotor lockup by applying a small lockup voltage to the stator windings. The number of poles must be entered correctly for the electrical angle to be correct.

We do not currently have alignment information for the Unico motors using the Hengstler/Unico encoders.

Count

The Count frame displays the encoder count both as a decimal and hexadecimal number. Users will typically be interested in only the decimal count, but encoder repairmen and other advanced users may find the hexadecimal representation useful. This is an absolute encoder, and it will remember the count on power up.

The Hengstler/Unico serial encoder produces a count of 4,096 (12 bits) per revolution. In addition, they count up to 4,096 full revolutions, so the count can range -8,388,608 (800000 HEX) to +8,388,607 (7FFFFF HEX). (24 bits - 12 bits for count per revolution and 12 bits of revolution count). The data is in gray code, but the TI-5000JX automatically decodes it and displays it as a binary count.

As mentioned previously, the count increases when rotated in the CW direction when the Direction* line is disconnected. Connecting the Direction* line to the 0V Signal line reverses the direction.

Always verify that the encoder count appears to change by the correct number of counts/rev while turning the encoder. If the count is not changing, then there is an encoder problem. As described in a later section, the Count Test may be performed to more accurately determine whether the correct number of counts per revolution is occurring, but this is an important initial evaluation.

Encoder Status

INDEX – The INDEX box is disabled for Hengstler/Unico serial encoders because these encoders display the correct count on power up without indexing.

DATA - If no data is being sent from the encoder, NONE will be displayed in the DATA box. If the TI-5000JX and the encoder are communicating correctly, RECEIVING will be displayed in the DATA box. The cabling is the first thing to check if the encoder is not communicating, but it can also mean a component failure in the encoder.

INTERNAL ERROR - The currently supported Hengstler/Unico encoders provide one error bit which is reported in the Error field. This bit is reported under the Error column with an "ALARM" message if it is HI. If this bit is LO, an "OK" message results. Hengstler/Unico literature indicates that causes for alarms could be low voltage, high temperature, broken disk or faulty LED.

BATTERY - The BATTERY box is disabled for Hengstler/Unico serial encoder because they do not utilize battery backup.

OVERHEAT - The OVERHEAT box is disabled for Hengstler/Unico serial encoders because they do not report overheat conditions.

ENCODER ID – The ENCODER ID box for the Hengstler/Unico serial encoders because they do not provide ID information.

Count Test

The Count Test can be started by clicking on the Count Test button among the test buttons at the top of the display. The Count Test will verify that the encoder is incrementing the correct number of counts per revolution. The Count Test for the Hengstler/Unico encoders is not significantly different from that for other encoders, so please refer to the general information on the count test in Section 2.2.2 for further details. The stuck bit test will test bit0 to bit11 for activity for 4,096 count 12 bit encoders. The stuck bit test is run on the gray code data read from the encoder rather than after conversion to the binary data.