This provides information for people wishing to receive serial data from Pulsar and Clay Paky controllers or to drive Pulsar and Clay Paky lighting equipment.

SERIAL FORMAT - 9600 baud, 1 start bit, 8 data bits, 1 stop bit, no parity. The data stream may be fully packed.

CABLE - For RS423 operation, use 2 core screened cable. Screen = Chassis Ground - connect at both ends,
Cores: Signal, Signal Ground (which must NOT connect to the screen or chassis). For RS232 operation, over shorter distances, for example from the Masterpiece to the Screen Driver, single core screened cable may be used.

MAXIMUM LENGTH - RS423 1200m, RS232 100m.

TERMINATION - line termination is NOT required.

BRANCHING - no problem.

HANDSHAKING - not required - so RTS (Pin E or 5 on a BBC Micro or pin 4 on a 25 pin 'D' connector) and CTS (Pin D or 2 on a BBC Micro or pin 5 on a 25 pin 'D' connector) need to be cross linked at the computer.

RESOLUTION - up to 14 bits, but normally 8 bits (256 possibilities), older products used 7 bits (128 possibilities).

NO OF CHANNELS - 15,360 max. - the protocol allows 128 pages of 120 channels each - for future expansion!

REFRESH - not required. Data is latched by the receiving device. Only the changes need to be transmitted. However it is good practice to send the constant Levels and the Page Number from time to time - for example, when there are no changes to send.

TRANSMISSION PROTOCOL:
Address - A byte with bit 7 set is an Address i.e. a Channel Number. Channels Numbers in the range 1-120 are sent as 128-247. Channels Numbers in the range 121-240 are sent as 128-247 after having first changed the Page Number from 0 to 1 - see below. Level - A byte with bit 7 clear is a Level. ONE or TWO Level bytes with values of 0-127 follow an Address. For 7 bit resolution, only ONE byte need be sent. For 8 bit resolution, where bit 0 is Lo, only ONE byte need be sent. For 8 bit resolution, where bit 0 is Hi TWO bytes need to be sent with bit 6 of the second byte set. For future expansion, bit 5 to bit 0 of the second byte could be used, giving up to 14 bit resolution. If only ONE Level byte is sent, it will not be acted upon until the next Address is received. Bytes 248 to 255 are used for special codes: 248 sets all channels to the Level which follows e.g. 0 for Blackout. 249 changes Page Number to the ONE Level byte which follows (0-127). Each of the 128 possible pages allow you to address 120 channels. Receiving units default to page 0 (channels 1-120) at switch on. The Page Number remains in the new page until another 249 sequence is sent. 250-255 are used by Pulsar to send ASCII, Key Presses, Slider Moves & other Controller to Controller information.

EXAMPLES:
1. Put channel 10 to 50%
a) Send Page - 249, 0 (only necessary if the Page Number is not already 0 for channels 0-120)
b) Send Address - 137 (128 = channel 1)
c) Send Level - 64 (range is 0-127)
2. Put channel 150 to 100%
a) Send Page - 249, 1 (only necessary if the Page Number is not already 1 for channels 121-240)
b) Send Address - 157 (128 = channel 121)
c) Send Level - 127 ( 7 bit resolution)
or - 127, 64 ( 8 bit resolution)
or - 127,127 (14 bit resolution)

PRODUCT RESOLUTION:
7 BIT - Pulsar BBC Lighting Control Desk program, Intelligent Interface, Clay Paky Golden Scan controller and Golden Scan 1. 8 BIT - All other Pulsar and Clay Paky products.