X hits on this document





17 / 21

The networks with the GEN_IO and AUX_IO labels provide a simple way to view all the MMC discrete input and output conditions using the ladder animation.

The subsequent networks provide support for jogging and homing the axes. When jogging, only one axis can be selected and it can jog in one of three modes: at a constant velocity, to a specific incremental distance, or as a follower to a handwheel. Note that jogging will stop when a travel limit is reached because an e-stop will occur (in the ESTOPACT's coil network). However, if the Machine Start push-button is being pushed at the same time as the jog button, the operator can jog off a specific over-travel. For instance when in velocity mode, if the axis is on the plus over-travel switch, the axis cannot jog in the plus direction but it can jog in the minus direction.

The last networks in the basic examples provide support for the referencing (or homing) of the servo axes. The M_FHOME function block supports a homing sequence for the axis using the axis fast input as the reference switch. The M_LHOME function block supports a homing sequence for the axis using a specific discrete input as the reference switch. Both function blocks are provided for each servo axis in the ladder with M_FHOME actually connected to the rail. If the M_LHOME functionality is desired, then its code fragment (the function block and the surrounding elements) can be cut and pasted over the M_FHOME area.

Operator Interface Application Examples

The examples having operator interface support (MMC2_OI and MMC4_OI) have more ladder logic than the basic examples. Early in the ladder, the OI_SER function block enables the MMC variables (in the main ladder) that are given the G (global) attribute to be shared with the operator interface device (typically a Cimrex terminal) connected via an RS232 serial connection. Note that the global attribute is also used when the MMC is connected to an external PC via the Ethernet module and the MMC shares its data with the PC using the OPC Server technology.

There are a number of networks that update the state of the ALARM() Boolean array. This array is used to provide immediate indicators to the operator interface device regarding specific ladder conditions.

After the axis jogging and homing section of the ladder, there are several networks involved with the saving and retrieval of the axis setup data using a RAMDISK file. Rather than having the various motion rates or reference positions hard coded within the ladder logic, they can be set by the operator and saved in a RAMDISK file, AXSETUP.DAT.

The examples conclude with a few networks that are the basis for supporting other Cimrex features: trending or graphing and the control of the LEDs.

SERCOS Drive Interface Application Example

There is an example provided for the 8 axis SERCOS MMC unit. This example (MMC4_SOI) is an extension of the 4 axis MMC example with an operator interface. For the support of the SERCOS drives, several different ASFBs are used.

At the start of the ladder logic, the SC_INIT function initializes the SERCOS ring connected to the MMC. Each SERCOS application must have its own SERCOS setup configuration. The example uses SRC_MMC4 for its 4 SERCOS axis configuration. For an actual application, this SERCOS setup function must be replaced with the actual SERCOS setup configuration. The programmer's steps to do that are very similar to those for replacing the servo setup, except that steps 7 through 10 in the above procedure (when STARTING A NEW APPLICATION FROM AN EXAMPLE) are done with SERCOS setup, not servo setup. The example uses SRV_MMC4 for its servo setup configuration. For an actual application, this servo setup function must be replaced with the actual servo setup configuration, as previously described.

The S_CLOS1 function block will close the position loop for the configured SERCOS axes. This ASFB is different for SERCOS axes because the SERCOS drive itself might have error conditions to reset before the position loop can be closed.

The S_ERRORC function block provides all the significant error information for a specific SERCOS axis. This ASFB is different than M_ERROR because a SERCOS axis has additional error information.

The S_FHOME and S_LHOME function blocks provide support for the referencing of the SERCOS axes. They are different than M_FHOME and M_LHOME because the latching of the reference position is done within the SERCOS drive.

The S_IO_C function block is unique to a Centurion SERCOS drive application because the additional discrete input and output points at the SERCOS drive can be made available to the ladder.

Press Transfer Application Example

MMC-Cimrex Quick Start.doc


Document info
Document views70
Page views78
Page last viewedThu Dec 08 14:31:52 UTC 2016