Rs-232 Daisy-Chaining - Parker Gemini GT6 Series Hardware Installation Manual

RS-232 Daisy-Chaining

36
Gemini GT6 Hardware Installation Guide
Up to ninety-nine stand-alone Gemini drive products may be daisy-chained. Refer
to the wiring diagrams for daisy-chain connections.
Follow these steps to implement daisy-chaining:
Step 1
To enable and disable communications on a particular drive unit in the chain, you
must use the Daisy-Chain Address (ADDR) command to establish a unique device
address for each unit. The ADDR command automatically configures unit ad-
dresses for daisy chaining. This command allows up to 99 units on a daisy chain to
be uniquely addressed.
Sending ADDRi to the first unit in the daisy chain sets its address to be (i). The
first unit in turn transmits ADDR(i + 1) to the next unit to set its address to (i + 1).
This continues down the daisy chain until the last unit of (n) daisy-chained units
has its address set to (i + n - 1).
Note that a drive with the default device address of zero (0) will send an initial
power-up start message similar to the following:
*TREV-GT6-U8_D1.0_F1.0
Step 2
Connect the daisy-chain with a terminal as the master.
To allow daisy chaining you must turn on echo mode for each drive on the chain
(ECHO1). The ADDR command automatically leaves each device in echo mode
after the device address is set when in RS-232 mode.
In the Gemini, daisy chaining can work in all error levels except error level 0 (see
ERRLVL command). To set the drive error levels to your preferred state you can
address each drive individually or send a global command. Note the address
syntax used to send data to particular units:
Commands:
1_ERRLVL4 ; Set error level to 4 for unit #1
2_ERRLVL4 ; Set error level to 4 for unit #2
ERRLVL4 ; Set error level to 4 for all units on the chain
Unlike ASCII-based products, the binary prompts associated with the different
error levels can pass through the daisy chain to the terminal controller without
interfering with the other drives. At that point they are translated into the text
strings defined by the ERROK and ERRBAD commands. Consequently, error
levels using prompts can be used in Gemini daisy chains.
To receive data from a particular drive on the chain, you must prefix the command
with the appropriate unit's device address and an underline:
Commands:
1_DRES ; Request drive resolution from unit #1
*DRES25000
Use the E command to enable/disable RS-232 communications for an individual
unit. If all drive units on the daisy chain are enabled, commands without a device
address identifier will be executed by all units. Because of the daisy-chain's serial
nature, the commands will be executed approximately 1 ms per character later on
each successive unit in the chain (assuming 9600 baud).
; Response from unit #1