Intelligent Motion Systems Modular LYNX System L f a x i s O p e r a t i o n F o l l o w e r

by a motor mounted encoder. The actual count of encoder pulses received by the Control Module is maintained by the register CTR2, (if the encoder is connected to I/O line pair 13 &14) with the EUNIT variable scaling it to user units. Example:

User Unit (POS) = CTR2 ÷ EUNIT where EE (Encoder Enable) Flag = TRUE(1)

When using the EUNIT scaling factor it is important to understand that you MUST set the EUNIT variable AND the MUNIT variable to the same scaling factor for accurate position monitoring. In the example below you will use a hypothetical system designed from the following components:

An IMS IB462H Half/Full Step driver configured for Half Step Operation.

A 1.8° Stepping Motor mounted to a 20cm linear slide.

A 200 Line Encoder.

You will want to use millimeters for our user unit. The IB462H in half step mode will need 400 clock pulses to turn the motor one revolution. The pitch on the leadscrew is such that one millimeter of linear motion will require 25 clock pulses. 400 steps/rev ÷ 25 steps/mm = 16 mm/rev. Therefore, you would set the MUNIT variable as follows:

MUNIT = 400/16

Now, when you give a MOVR 20 instruction, the axis will index 20 millimeters. Now to set the EUNIT Variable. We have a 200 line encoder connected to a quadrature clock input. This will mean that 1 revolution will equal 800 Encoder Pulses, you will have to use the same scaling factor as we did for MUNIT as there will still be 16mm per revolution:

EUNIT = 800/16

Both values must be set, and both must be set to the same scaling factor. With the EE = 1 a MOVR 20 command will still index the axis 20 millimeters, but position will be maintained by CTR2.

H a l f A x i s O p e r a t i o n ( F o l l o w e r )

In half axis mode the master clock is taken from a clock input 2, 3 or 4 (line pairs 13-14, 15-16 or 17-18) which have been set for input, clock type and ratio enabled. This is the factor at which the count rate out to the primary drive will follow the external clock in half axis mode. This clock input would typically be connected to differential input pairs 15 and 16 (P1, pins 5 – 8). This could be set up as any of the available clock types. If half axis mode is enabled (HAE), the primary axis of the control will follow the clock input with the ratio specified by the HAS variable.

In order to use the HAS (Half axis mode scaling) variable the HAE flag must be set to true (1). For example, to set the half axis scale factor to .5, where the drive will follow the external Clock input with a ratio of 1 count to the drive for every two counts from the external clock, you would use the command: SET HAS = .5 (or HAS = .5). Figure 6.9 illustrates the connections for using this mode of operation using a clock input from an encoder.

The sequence of commands used to make this setup function would be as follows:

‘Set IOS 15 to ratio mode

IOS 15 = 5,0,1,0,1,1

‘Set IOS 16 to ratio mode IOS 16 = 6,0,1,0,1,1 ‘Half axis enable set to true

HAE = 1

‘Half axis scaling to .5 (1 output clock pulse to every 2 input clock pulses) HAS = .5

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