V Memory
TMC 188/40 Motion Control Module
Delta Computer Systems, Inc. 360/254-8688
16
WY Register and V Memory Image Descriptions
The TMC 188/40 communicates with the P/C through a Special Function Interface Chip (SFIC) and V
Memory. The SFIC has been configured to appear as eight WY registers
in the P/C‟s I/O area. The
WY registers are used to tell the TMC 188/40 where the control parameters are located in V
Memory (pointers to V Memory). Once the WY registers are initialized all communication between
the P/C and the TMC 188/40 is done through V Memory.
Six of the eight WY registers are used as pointers to V Memory locations, one is reserved as a
pointer to the start of the Event Steps Table, and the last is used to pass a checksum of the first
seven registers. V Memory is used to pass parameters, receive data, and direct the module to
specific action. During a P/C scan, the I/O operations are executed first, followed by the ladder logic,
and then SFIC functions. The ladder logic program must contain the steps necessary to initialize the
WY registers as well as set up the required control parameters in V Memory.
WY Registers
For the TMC 188/40 to work, you must set up eight consecutive WY registers as shown in the
following table. Each WY register contains the V Memory address of the first location of a continuous
list of parameters. After the WY registers are set up, all communication between the P/C and the
TMC 188/40 passes through V Memory. The following pages list the VINIT, VREAD and VWRITE
parameters used by the TMC 188/40. If the analog
option is installed (indicated by an „A‟ suffix: TMC
188/40TA), the VINIT V Memory is expanded (see Appendix B for details).
WY
Register
Type of Parameters Description
1
VINIT
Axis 1 V Memory address of initialization parameters
2
VINIT
Axis 2 V Memory address of initialization parameters
3
VINIT
Axis 3 V Memory address of initialization parameters
4
VINIT
Axis 4 V Memory address of initialization parameters
5
VREAD
Axis 1-4 V Memory address of position and status data
6
VWRITE
Axis 1-4 V Memory address of dynamic control
parameters
7
Reserved
Zero, unless using Event Control Firmware
8
CHECKSUM
WY1+WY2+WY3+WY4+WY5+WY6+WY7 (16 bit, no
carry)
NOTE:
The TMC 188/40 will not operate if the CHECKSUM is incorrect.
NOTE:
The WY registers
can be any block of eight consecutive registers in the P/C‟s I/O area (they
don't have to start with WY1). If there is more than one TMC 188/40 in a system, each one
must have its own set of eight WY registers. The first four WY registers must contain the
address of the V Memory where the initialization parameters for their respective axis are
stored. You must enter the sum of the numbers in the first seven registers into the eighth register;
this is the checksum used by the controller to verify the register data is valid.
