User manual

Chapter 5 PLC-5 BT Instructions

ADVANCED MICRO CONTROLS INC.

PLC-5 Restrictions and Warnings

The following restrictions must be followed when using the 2762-

17 in a PLC-5 System. If these restrictions are not followed,

unpredictable operation may occur.

1. The 2762-17 will not operate in a chassis configured for 2-Slot addressing. The chassis must

be configured for 1-Slot or ½-Slot addressing.

2. The 2762-17 module must be installed in a single slot pair. (See chapter 3,

Installing the

Module,

page 37.) If it is not installed correctly, the module will not be able to perform

concurrent block and single transfers.

3. When using the 2762-17 in a remote chassis, the Remote I/O Adapter must be a 1771 - ASB,

Series B, Firmware Rev. F, or later. Using a Remote I/O Adapter that has an earlier Series or

Firmware Revision may not work properly with the 2762-17.

4. When the processor enables a block transfer, it puts all of the needed information into a queue.

A queue is a data structure where the first piece of information put into the queue is the first

piece of information taken out. Once the information is queued, a separate part of the

processor performs the block transfer while the rest of the processor continues with the

program scan. Each I/O rack in the system has it's own queue. Each queue can hold 17 BT

requests. When the block transfer has its Continuous bit set to 1, Continuous Parameter is

"YES", the Block Transfer is placed permanently in the queue.

Each queue has a "Queue Full" bit in word 7 of the processor's status file. Bit 8 is for Rack 0,

Bit 9 is for Rack 1, and so on up to bit 15 for Rack 7. The appropriate bit is set when a queue

is full of BT Requests. Once set, your ladder logic program must clear these bits. We recom-

mend that your program monitor these bits and take appropriate action if these bits are set.

Note

: If you have more than 17 block transfers associated with one rack and you set all of their

continuous parameters to YES, only the first 17 block transfers scanned will be

performed. All other transfers cannot be put into the queue and will never be performed.

WARNING